The Reagan administration will shortly announce an agreement with the People's Republic of China limiting future U.S. arms sales to Taiwan, informed sources said yesterday.

At the same time, the sources said, the administration has informed members of Congress that it will go forward with the long-promised approval for continued U.S. coproduction with Taiwan of F5E jet fighter planes.

By planning to make both announcements about the same time, the administration seemed to be offering something to both sides in the China dispute, but it is unlikely that either will be completely satisfied.

The agreement with Peking, the culmination of intense diplomatic discussions between the two governments that began in January, is intended to settle the longstanding Sino-American dispute over Taiwan arms.

However, sources familiar with the proposed text of statements by the two governments described them as susceptible to varying interpretations, and thus more of a temporary palliative than a permanent settlement of the politically explosive issue.

The expected announcement is likely to bring protests from some conservatives in Congress and elsewhere who are already upset with President Reagan's policies on the economy and other issues.

Sen. Barry Goldwater (R-Ariz.) said he objects to the language he has seen of the proposed U.S. statements because they speak of "quantitative and qualitative" limits on its future arms supply to Taiwan. Such limitations, he charged, are in essence a violation of the Taiwan Relations Act, which declared that the president and Congress will make continuing sales of arms to Taiwan "based solely on their judgment of the needs of Taiwan."

Goldwater said the planned limits on quality and quantity of U.S. arms sales would require serious reductions over time, because of inflation and the constant technological improvement in military weaponry. Goldwater said "it bothers me" that the implementation of the limitations a few years from now could be in the hands of a president who is less friendly to Taiwan than Reagan, including Vice President Bush, who Goldwater described as "oriented toward Red China."

Asked if he anticipates a major battle in Congress on the issue, the Arizona senator noted that a U.S. diplomatic arrangement embodied in letters or a joint communique with Peking does not require congressional approval. This fact makes binding legislative action difficult.

The dispute with China flows out of a failure to settle the Taiwan arms question during the Sino-American negotiations leading to the normalization of relations between the two countries in January, 1979. The Carter administration, in announcing the normalization, made it clear that U.S. arms sales would continue. China never agreed to this continuation, but normalized its relations with Washington nonetheless.

Reagan, under pressure from both sides on the issue, decided in January to reject the proposed sale of a sophisticated FX fighter plane to Taiwan, but at the same time approved continued U.S. coproduction of less advanced F5E aircraft, which Taiwan has been acquiring for some time.

Peking rejected the continuation of the existing Taiwan warplane contract and threatened to downgrade its relations with Washington, including withdrawal of its ambassador here, unless a long-term settlement of the issue could be reached. Such a deterioration in Sino-American relations could have important strategic consequences, in the view of then-secretary of state Alexander M. Haig Jr. and other administration officials.

Early in the negotiations, China demanded that the United States establish and announce a cutoff date for all U.S. arms to Taiwan. However, it abandoned this position after the administration convinced Peking's leaders that it could not and would not set such a date.

U.S. statements projecting limitations on the future quantity and quality of arms to Taiwan, along with a disavowal of long-term arms arrangements and acknowledgment of Chinese sovereignty, are much less binding than the assurances that Peking continued to request.

These self-imposed restrictions are made possible,in the view of U.S. officials, by the recent decline in military tension between China and Taiwan. An escalation of military tension in the Taiwan Strait might well mean the United States would have to reconsider its stand.