China has failed to give any assurance that it will live up to its trade agreement with the United States to buy a specified amount of grain this year, an Agriculture Department official said yesterday.

Richard A. Smith, administrator of USDA's Foreign Agricultural Service, said the pact was discussed in consultations held in Peking this week. The agreement, signed on Oct. 22, 1980, expires at the end of this calendar year.

"The U.S. delegation expressed its deep disappointment over China's noncompliance with the terms of the agreement and requested the Chinese to fulfill their import commitment as soon as possible," Smith said.

Under the terms, China is supposed to buy a minimum of at least six million metric tons of wheat and corn each year.

"During the first two years of the agreement, shipments of U.S. grain to China exceeded the minimum import commitment," Smith said. "However, for the last two years, cumulative Chinese purchases for shipment through calendar 1984 total only 8.2 million tons -- 3.8 million tons short of the agreed minimum."

Last year's sales included about 2.45 million tons of wheat and 1.38 million tons of corn. For 1984, so far, sales include less than 4.42 million tons of wheat only.