Adjusting to the reality of a Ronald Reagan presidency, West German Chancellor Helmut Schmidt has shifted ground on the subject of paramount importance to him -- strategic arms limitation talks -- moving to a point where, to his relief, he and president-elect Reagan could agree.

Schmidt no longer advocates, as he did while the U.S. election campaign was in progress, that the second Strategic Arms Limitation Treaty be ratified by the U.S. Senate. He accepts that Reagan opposes the treaty and that a majority of the new Senate will also.

In a major policy address Monday, the West German leader indicated it was enough for him that the SALT process be continued in some other form. He said Reagan wants the same and told Schmidt so during their meeting in Washington last week.

This reassurance, together with the friendly reception Schmidt felt he got from Reagan's camp, is viewed by many European officials as a very encouraging first step in establishing good relations with the incoming Republican administration.

West German observers noted that when Schmidt returned from his visit and delivered his speech to the Bundestag, West Germany's friendship with the United States more strongly than he had in statements earlier this year when Bonn and Washington were at loggerheads over how to respond to the Soviet invasion of Afghanistan.

Prior to the U.S. election, Schmidt, of all the major European allied leaders, was thought to have the most trouble coming to terms with a possible Reagan presidency. The Bonn government's heavy political investment in arms control, disarmament and cooperation with the Soviet Union appeared to contrast sharply with Reagan's stated intention of putting strengthened Western defense efforts before arms negotiations with the Soviets.

And yet, in the election aftermath, Schmidt has been quick to embrace Reagan, saying he looks forward to new decisiveness in the White House and closer consultation with Washington.

There is a large dose of political pragmatism in this warm welcome, of course. Having started off poorly with President Carter four years ago, government officials have been faster this time to shed their reservations -- or at least hide them -- about America's new chief.

Moreover, they genuinely see the chance for a smoother relationship with a Reagan team that could include such old acquaintances from the Nixon and Ford eras as George Schultz, Alexander Haig and Henry Kissinger. They tend to overlook the strains that existed in Bonn-Washington relations even when these experts were in charge.

"We had been cautious and wary for four years," said Peter Corterier, a Bundestag member and leading foreign-affairs expert in Schmidt's Social Democratic Party, explaining the Bonn government's warm welcome for Reagan. "If we had decided to start off the same way with Reagan, where would that have left us?"

So far Reagan has made the courtship easy by stressing two points of vital importance to Schmidt -- consultation with America's European allies and additional arms talks.

But will the chancellor, who has supported closer relations with the Soviet Union, really get along better with a Republican president known as an East-West hard-liner? Will the past conflicts between West German assertiveness and American leadership now be absorbed in the framework of closer consultations?

West German government officials say they are under no illusion that relations with the Reagan administration will be easy.

The fundamental questions that have strained the alliance partnership in the past -- how far to cooperate with the Soviet Union, what constitutes an adequate defense, and what to do in the Middle East and the Third World -- remain diplomatic problems.

Although Schmidt and Reagan agreed on keeping the SALT process going, neither the West German leader nor the president-elect pressed the other on what this means, knowing neither really had a definition at that point, according to West Government sources.

There could be problems working out such a definition. Leading Social Democrats, including Party Chairman Willy Brandt, are not as willing as the chancellor to let go of the SALT II treaty and believe that the Soviets will not be either, without setting a stiff price at the negotiating table.

For now, government officials say Schmidt is satisfied to have received Reagan's personal assurance that the president-elect will pursue new arms talks along with improvements in Western defenses.

Moreover, Bonn officials have found additional encouragement in what are viewed here as apparent signals from Moscow that ratification of SALT II may not be necessary for continued talks.

"We are for the time being satisfied with events," said a well-informed government source. "Certain signals coming out of Moscow and Washington seem to be the same."

The other signals Schmidt worries about are those from his own economy, which have not been as encouraging. Recessionary pressures, reflected in projections for next year of near-zero economic growth for West Germany, threaten to curb Bonn's recent moves toward an expanded world political role.

A limited 4 percent increase in the national budget has been imposed for 1981 to deal with an oversized federal deficit that has become particularly worrisome for the government in view of a weakened West German mark.

With Reagan on the ascent and Schmidt in a holding position, time will tell whether the political intersection the two leaders reached on SALT was a temporary convergence or the beginning of a long-term relationship.