Relations between the United States and China are strained over Washington's sale of arms to Taiwan and the detention of an American graduate student in Peking. But US and Chinese officials are continuing efforts for an unprecedented agreement which would open the way for US companies to bid for a role in China's nuclear power program.
In a separate step, the Reagan administration is moving to improve relations with Peking by asking Congress to update laws that specifically bar China, as a communist country, from receiving food aid.
Those moves are likely to increase concern on Taiwan and in some parts of Southeast Asia that despite all the publicity about the rift between Washington and Peking, events may be moving too far in the other direction.
According to Deputy Secretary of State Walter Stoessel, the nuclear talks, described as preliminary discussions so far, are breaking new ground in US nuclear export policy.
For the first time the US is talking about a nuclear cooperation agreement with a country that has the atomic bomb, has not signed the Nuclear Non-Proliferation Treaty, and refuses to accept international safeguards against diversion of nuclear material into weapons.
Instead China would be expected to give ''reasonable assurances'' that material from reactors supplied by the United States would not be used to make weapons, officials said.