Negotiators for the United States and its major trading partners ended two days of conferences here yesterday with all sides reporting visible progress toward hammering out a trade package for consideration by the seven-nation economic summit in Bonn next month.

Although none of the participants apparently made concessions on specific issues, sources reported the negotiators reached a firm understanding of where each party stood on key proposals, and that "compromises now are expected all along the line."

Moreover, the negotiators set a crash timetable for the next three weeks to try to wrap up work on a broad proposal before the July 16-17 summit. Robert S. Strauss, the U.S. special trade representative, said "we now have in hard and final form . . . what the bottom line issues are.

Although the "progress" the negotiators reported appeared to be more in procedure than in substance, the results clearly left officials more optimistic than they had been before the sessions began. U.S. negotiators, in particular, had been relatively cautious.

Sources said the U.S. apparently has signaled its willingness to give the Europeans much of what they want on such key demands as informal arrangements to stablize agricultural commodity prices and requirements for proof of "injury" before taking action against subsidized exports.

At the same time, Americans officials apparently were encouraged by European and Japanese responses to Washington's demands that they open up their markets to more U.S. farm exports. The U.S. also is seeking tighter restraints on government subsidies of foreign exports.

The U.S. also appeared to have been successful in persuading Japan and Europe to consider Canadian trade demands more seriously. The U.S. is seeking key trade concessions from Canada, but Ottawa has said it cannot grant them unless it in turn receive a break from European and Japan.

The deadlines the negotiators set yesterday involve two "interim" target dates before the July summit:

First, to complete work by June 30 on a series of proposals for reducing non tariff barriers, and, second, to work out agreement on the agricultural question by July 10-12.

Although the interim sessions will be conducted by deputies, the negotiators also pledged to remain on call for further ministerial-level talks. Strauss told reporters yesterday "the odds are in our favors" that "we can meet substantially" the deadlines of the July 16-17 summit.

The summit deadline is important because the negotiators want to give the trade talks added impetus with the endorsement of the seven heads of government who will be attending the Bonn summit. Without this, some officials say, the trade talks could bog down again.

Strauss was accompanied at the news conference by the three other negotiators, Wilhelm Haferkamp, vice president of the European Economic Community; Nobuhiko Ushiba, trade negotiator for Japan; and Jack H. Warren, trade representatives for Canada. The rest seemed to endorse his views.

The seven nations scheduled to attend the July summit include the U.S., the United Kingdom, West Germany, Japan, France, Italy and Canada. The session will be in first since the London economic summit meeting held in May of 1977.

The proposals the negotiators are drawing up involve broad outlines of basic agreements on new codes of conduct involving a reduction of trade restrictions in five areas:

Government-mandated product standards that serve as barriers to trade, such as labelling and packaging requirements, auto emissions standards, and food and drug regulations.

Government export subsides and other aid to specific industries, such as European underwriting of steel producers, which U.S. negotiators say provides an unfair price advantage to overseas firms.

Rules and regulations by individual governments that effectively prohibit foreign companies from bidding on government contracts for the purchase of goods or services.

Limits on the use of "safeguards" - temporary trade restrictions now allowed under current international trade rules to protect domestic industries against sudden surges of foreign imports.

Revamping of present customs valuation systems, many of which are designed intentionally to hold down imports. Europeans particularly object to the longtime American Selling Price system for chemicals.

Strauss also hinted yesterday that the major nations may drop a U.S. bid to work out a worldwide agreement on steel as part of the new trade pact. "I don't know what - if anything - we will do on that," he said in answer to a question on the steel talks.

While generally optimistic about the prospects, Strauss tempered his comments yesterday repeatedly with the warning that "this last 10 per cent of the issues is the tough part" and that "there's no guarantee" the negotiators will be able to reach agreement.

He said if the negotiators do reach agreement before the Bonn summit, the trade talks will be "substantively completed by the summer" and drafting should be completed in time to present the pact to Congress in January. "We're over the hump," he told an audience yesterday.