The Reagan administration announced Wednesday it is lifting sanctions on sales of new high technology to China because it is satisfied that country is not selling Silkworm anti-ship missiles to Iran.

Secretary of State George P. Shultz informed Chinese Foreign Minister Wu Xueqian during a meeting Tuesday afternoon that the restrictions would no longer apply.For years, the United States has continuously increased the types of high technology products China could purchase from U.S. companies. To protest the missile sales, however, the administration froze that process last autumn.

We are encouraged by Chinese statements and actions regarding Iran's acquisition of Chinese anti-ship missiles, Silkworms, State Department spokesman Charles E. Redman said.

We have therefore decided to resume the export control liberalization process for China, he said.

During a 40-minute meeting with President Reagan this week, Mr. Wu also said his country would not stand in the way of a United Nations resolution calling for an arms embargo against Iran, White House spokesman Marlin Fitzwater said.

The United States has been trying for months to line up support on the U.N. Security Council for an arms embargo against Iran designed to stop the seven-year-old Iran-Iraq War. The ban on weapons sales would be the second installment of a U.N. resolution last July calling for a truce in the war.

U.S. officials who estimated in recent weeks that China sold $1 billion in weapons to Iran in 1987 said they did not expect China - a permanent member of the U.N. Body - to veto the arms ban. Mr. Fitzwater's report on Mr. Wu's meeting with Mr. Reagan appeared to solidify that view.

The spokesman quoted Mr. Wu as saying, If the overwhelming majority of the Security Council believed it should be adopted, including the arms embargo, they are in favor; there was no difficulty on their part in terms of that second resolution.

The final step in the resolution would be Soviet support. U.S. officials have said Moscow appears willing to lift its objections to an arms embargo if it is accompanied by a short period of further diplomacy - one last effort to get Iran to agree to a cease-fire.

Mr. Fitzwater said of Mr. Wu's assurances, It was our reaction, the president's reaction, that this was a very positive sign, a very strong expression of support and one, frankly, one we hope the Soviet Union would emulate.

Of all the weapons China has sold to Iran, Silkworm anti-ship missiles used in attacks on tankers in the Persian Gulf have caused the most consternation to neutral countries.

The United States repeatedly protested to China about the sales last year, but since last autumn, U.S. officials have said they believe the Chinese are no longer sending the missiles to Iran.