Peking — As China and the Soviet Union prepare for their second round of ''consultations'' aimed at improving relations, both sides seem agreed on two general points: (1) they desire better relations, and (2) serious obstacles bestrew the way.
China has frequently defined the three major obstacles to better relations as: the ''million'' troops Moscow has on China's border and in Mongolia, the Soviet occupation of Afghanistan, and Soviet support for Vietnam's occupation of Kampuchea. The Chinese say they are not demanding progress simultaneously on all three points.
Soviet sources say China's demands are difficult to meet because they involve third parties - the Karmal regime in Afghanistan, Vietnam, Mongolia.
For instance, why are Soviet troops in Mongolia? asked one Soviet source. It is because Mongolia fears China. Let China talk directly to Mongolia and remove these fears.
As for the thinning-out of Soviet troops on the Sino-Soviet border, Soviet sources point out that their main supply artery, the trans-Siberian railway, runs very close to the Chinese border. Chinese troops in Manchuria might withdraw from border regions to cities and bases further inland. But how far should Soviet forces withdraw to satisfy the Chinese? Beyond the Banam railway now being built north of Lake Baikal?
There is also the question of SS-20 mobile missiles in Siberia, which are being built up as steadily as those in European Russia. China and Japan share a common interest in putting a stop to this buildup.
The first round of talks was held in Peking last October. The second round begins between deputy foreign ministers Qian Qichen and Leonid Ilychev in Moscow March 1.
Whereas in the first round each side stated its basic position, the second round may see the beginning of a real dialogue. No early breakthrough is expected.