In the first detailed Soviet analysis of French policy under Francois Mitterrand, the Communist Party newspaper Pravda expressed grave doubts yesterday over the course followed by the Socialist president in foreign affairs.

Pravda's editor-in-chief, Viktor Afanasyev, who is also a high-ranking party official, indicated particular concern over Mitterrand's views on nuclear weapons in Europe.

Publication of the article coincided with the French president's departure for the United States for a meeting with President Reagan that is expected to underline a joint stand on East-West relations and the defense of Western Europe.

It was also critical of the French leader's stand on the Afghanistan question, which Paris sees as an obstacle to normal relations with Moscow. The article indicated that Moscow now feels its deep reservations about Mitterrand, hinted at before his election last May, have been fulfilled.

Hinting at Soviet fears that Mitterrand was moving France further into Washington's orbit, Afanasyev wrote: "Will the allegiance of France to the Atlantic Alliance grow into Atlantism? This is dangerous both for France and for peace in Europe."

Another commentary to be published in Pravda Sunday contains an attack on a U.S. Defense Department booklet titled "Soviet Military Power," calling it "rotten fruit of Pentagon propaganda" and a "big lie" designed for "simpletons."