WASHINGTON (AP) _ Secretary of State George P. Shultz and leading Chinese policy-maker Yang Shankun pledged on Tuesday to take steps to increase trade between the United States and China, U.S. officials said.

Yang, vice chairman of China's central military commission and a close confidante of Chinese leader Deng Xiaoping, met with Shultz for two hours at the State Department.

Yang's two days of talks in Washington will continue Wednesday when he meets President Reagan.

Neither Yang nor Shultz would answer questions at the end of their meeting, but U.S. officials speaking on condition of anonymity said much of the discussions centered on economic issues.

The United States, as it has with other countries in Asia, is urging China to open itself to foreign investment - a step China has pledged to do by changing laws that discourage U.S. businessmen from beginning ventures in China.

China also is eager for liberalization of U.S. rules limiting the transfer of high technology products to China. Yang raised the issue again at the session and Shultz promised to take all possible steps to speed the flow of technology, the officials said.

Shultz also made an effort to assure Yang that the Reagan administration opposes protectionist trade measures, which China fears might reduce its exports to the United States.

U.S.-China trade totaled $9 billion last year.

The officials said Shultz also briefed his visitor on U.S.-Soviet arms control negotiations, which are of concern to China.

The United States and the Soviet Union have agreed in principle to eliminate long-range intermediate nuclear missiles in Europe, but the plan would allow both sides to retain 33 missile launchers of that type outside the European theater.

That would leave 33 Soviet rockets in Asia, where they could be targeted toward China.

The United States has said it will continue to work for a total elimination of the missiles, but would agree to limited retention of the Asian rockets in the interim. China and Japan have expressed concern about any deal that would leave intermediate-range Soviet missiles in Asia but have not tried to block the U.S.-Soviet plan.