Despite the generous play which Polish television gave to the World War II allies on Victory Day recently, Polish-Western relations - above all Polish-US relations - are at their worst in a generation. Periodically chilled, they never reached as low as now.
Daily, police mount close watch at the US Embassy in Warsaw to note identity cards and turn away all without ''valid'' business. Today that means admitting only Poles showing a passport and there to ask for an American visa.
The authorities have placed the embassy library off limits as reprisal for what is described as the anti-Polish ''unfriendly propaganda campaign'' in Voice of America and Radio Free Europe broadcasts in Polish. It seems an ineffectual tit-for-tat against the more serious background of the dip in a traditional relationship rooted in America's own struggle for independence. The ban militates mostly against young Poles anxious to consult or borrow reference works and literature relevant to their studies, as did the generation before them.
The step, one may presume, was dictated by Warsaw's ideological hardliners rather than by the diplomats of the foreign ministry. Some long involved in US affairs, both here and in Washington, must now defend it. They seem genuinely sad as well as bitterly critical of the United States about the turn relations have taken.
''But what else could we do?'' a senior ministry official demands. ''We countenanced it (Poles' access to the library and its movie shows) for years, without any agreement or similar outlet for ourselves in the US. In view of the Reagan administration's continuous hostility we decided it could not not go on.''
It used to be that he and other usually moderate-minded officials talked of allowing Washington some ''benefit of the doubt.'' That, however, has given way to resentful assertions that Washington, especially the White House, ''does not not want to understand'' the reality behind all that has happened since August 1980, that it sees Poland and its instability as merely an instrument to advance a presidential obsession with Russia and a crusade against ''the greatest evil on earth.''
Being Poles, they may privately deplore the way the chips fell in Central Europe after the war. But they accept it - and expect the West to do the same - as part of the geopolitical reality of their country, wedged in between powerful neighbors. They are, moreover, unequivocal in stating that Poland's security is more assured today than at any time before.
''You have to remember,'' says one of the most experienced foreign affairs experts here, ''it was the Russians who drove the Germans out of Poland and restored the Polish state. But for them, we would have again ceased to exist as a state. We would never have gained our present western border. Many of our own romantically minded young people - I'm not concerned with the opposition - need to remember this, too.''
Since February there has been no American ambassador here, though Washington has named a career foreign service officer, John Scanlan, for the post. Having served in Poland three times previously, Polish-speaking Mr. Scanlan is well known to the Poles, and apparently well respected. The authorities are withholding approval, however. ''We have nothing against Scanlan,'' the foreign ministry official said. ''But while US attitudes remain as now we are leaving our answer open.''
He and others like him insist that the Jaruzelski government has given enough signals of intention to further ease internal conditions - and of a desire to lower Polish-US tensions - to warrant some shift on Washington's part.
In February the ministry sent the head of its American department, Jan Kinast , to Washington. ''We really meant it as a gesture,'' the official said. ''We really hoped his talks in the State Department might lead somewhere. But there has been no response from the US - none at all.''
Predictably, General Jaruzelski is concerned not to be seen in Moscow as making concessions under pressure from the Roman Catholic Church or the United States. The Soviet Union's dislike of the current papal visit, among other matters just now, is evident enough to an outside observer here let alone to Poles who must live with it.
Moreover, the Czechoslovak and East German leaders are pressing their own hard-line view of Poland on the Russians even more energetically than before. Each fears an impact of the papal visit among its own people. The Prague government, whose counterproductive crackdown on the churches has been intensified this year, is especially concerned.
Polish awareness of the hostility within the Soviet bloc seemed implicit in Vice-Premier Mieczyslaw Rakowski's reply to a US network which recently asked him about the possibility of Lech Walesa meeting with the Pope. That was a matter for the Pope, Mr. Rakowski said. There was no such meeting in the formal program. If there were one, however, ''we would not not be happy about it.''
Under such conditions, Jaruzelski could not conceivably give an outright, open yes to church and other appeals over amnesty for martial law offenders or to accept it as a US precondition for lifting economic sanctions.
The Pope knows well the pressures under which any Polish government must operate. He will therefore pursue Jaruzelski's recent hints of what could happen after the visit; and, though his visit is ostensibly a pastoral pilgrimage, he will utilize the opportunity for discussing obvious political issues with the Polish leader. One of these issues, moreover, will be the question of ''full diplomatic relations'' between the Vatican and Warsaw.
There is considerable feeling here now that, if the visit proceeds without incident, remaining aspects of martial law will be removed soon afterward. General Jaruzelski said as much in his recent speech to the ''conciliation''-oriented Patrio. Should the Pope leave with firm assurance on such points, this would probably be enough for most West Europeans to modify their present standpoint. It would be difficult for the United States not to do so also.