Washington — President Reagan, dressed in a brown suit and red tie, beamed as he greeted a delegation of Chinese students at the White House this week. They are among the more than 10,000 students from the People's Republic of China now studying in the United States.
''We'd like to see the 11,000 become 100,000, and we're going to work toward that goal,'' the President told them. Then he proceeded to greet each Chinese individually, as a White House photographer snapped the event.
The scene capsuled the visibly improving state of Sino-American relations on the eve of the President's trip to China. It also illustrated that Mr. Reagan's ideological aversion for communism does not mean he will not do business with communists - especially Chinese communists.
The six-day presidential visit, beginning April 26, will have broad diplomatic and political dimensions. The President expects to reap benefits on both counts:
* In foreign policy terms, Mr. Reagan seeks to consolidate the US relationship with China, which despite many ups and downs in recent years, is currently improving, and holds out promise for extensive bilateral economic cooperation.
At the same time, the President wants to enhance stability in the Pacific region. While the visit is not expected to produce major agreements, it will be extremely important in terms of Washington's growing involvement in Asia.
* In the domestic political context, the visit will give the President high media visibility as a pragmatic world leader at a time when his record abroad is under widespread criticism. A diplomatic tour de force in China could help his approval ratings at home in the foreign policy area.
Preparations for the presidential journey are hectically under way, and the White House seems gripped by excitement. China is not just any country. It's that land of dominating Oriental ambiance that has fascinated every American presidential traveler. Mr. Reagan, who will be the third US president to visit the People's Republic, is no exception.
In addition to the usual foreign policy briefings given him, Mr. Reagan has sought the advice of China scholars outside government. The purpose has been to find out what the Chinese are like and what he can expect in the Chinese environment, culturally and psychologically.
''He clearly is very enthusiastic and upbeat about the trip and very serious about preparing for it,'' says Winston Lord, chairman of the Council of Foreign Relations. Mr. Lord and his wife, Betty, also a China expert, were among several scholars invited to a private luncheon with the President recently.
''It's important to have a feel for the Chinese,'' adds Mr. Lord, ''particularly since he will be communicating with the Chinese people on television - which is unprecedented.''
It is also important to be rested, given the grueling schedule Mr. Reagan will have during the six-day visit in China. To overcome jet lag, Reagan will travel in stages. He leaves for his California ranch Thursday, and will make stops in Honolulu and Guam before flying on to Peking on the 26th.
Reagan political strategists are ecstatic about the opportunities the trip affords for putting the President at center stage.
''It's important for every president, especially when running for reelection, to highlight the differences between himself and the opponents who want his job, '' says a Reagan campaign official. ''The trip to China will highlight not only his foreign policy achievements but the contrast between him and the other three candidates in the race. While they're squabbling and trying to win, he will be seen as a world leader meeting with other leaders halfway around the world.''
The trip promises to be a media extravaganza, with Reagan ''on camera'' for a wide array of colorful events.
During his stay in Peking, the President will visit the Great Wall. He will also address the Chinese people on television, a first for an American president. ''The potential audience is 350 million to 400 million,'' a senior administration official quipped in a briefing for journalists.
The Reagans will also travel to Xian, the site of archaeological finds where life-size terra-cotta figures have been unearthed. In Shanghai, the last stop, the President will visit a factory where US industry is taking part in a joint venture. He will also talk with students at Fudan University and see a performance by Chinese chidren at a child-care center.
Diplomatically, the presidential trip will be a sequel to the visit of Chinese Premier Zhao Ziyang to the US in January. Reagan will have 10 hours of meetings with top Chinese leaders, but the trip is not expected to produce any breakthroughs on the issues still dividing the two countries.
The prickly issue of Taiwan is certain to be raised. But administration officials say that both sides will abide by their position. On Tuesday the President told Chinese journalists that the US ''will not turn our back on old friends in order to . . . strengthen or make new friends.''
At this writing it does not appear that a nuclear cooperation agreement will be concluded in time for the visit. But other minor accords, including a cultural agreement and a tax treaty, will be signed. Meantime, bilateral discussions on a business investment treaty, arms sales, and other questions will continue.
Administration officials stress that the prime importance of the visit lies in its potential for evolving ties with a major power. ''We could be on the eve of a new era in US-Chinese relations,'' a senior official commented this week, referring to growing commercial and other activities.
Outside China, experts also view the journey as significant for US foreign policy. ''It makes sense totally apart from domestic political considerations,'' says A. Doak Barnett of Johns Hopkins University. ''Our relationship went through a bad period, and there wasn't an upturn until this year. Both thought they needed to do something to repair it and put it on a more stable basis.''