West German Foreign Minister Hans-Dietrich Genscher met with Soviet leader Mikhail Gorbachev today for three hours on a visit widely viewed as the beginning of the end of three years of cold relations between Bonn and Moscow.

Genscher flew here after consulting with White House envoy Paul Nitze in Bonn to learn about the Reagan administration's draft response to the latest Soviet arms proposals. Nitze is touring several European capitals to inform U.S. allies about the American reply, which Genscher characterized as "constructive" with "far-reaching ideas."

The meeting at the Kremlin today represented the most extensive talks Gorbachev has held with a leading member of Bonn's ruling center-right coalition. Gorbachev encountered West German Chancellor Helmut Kohl only briefly at the funeral of Konstantin Chernenko, the Soviet leader's predecessor, in March 1985.

In a report on the Gorbachev-Genscher meeting, the Soviet news agency Tass indicated that Gorbachev underlined the impression that Moscow is prepared to normalize Soviet-West German relations. The Bonn-Moscow link has been strained since the deployment of NATO Pershing II missiles began in West Germany in December 1983.

Gorbachev emphasized "the mutual responsibility" of states like West Germany and the Soviet Union "for building a 'European home,' " Tass said.

The Soviet leader dropped the charges of revanchism and militarism commonly leveled by Moscow against Bonn in the past two years. He also apparently refrained from echoing Soviet complaints that Kohl's government toes the Reagan line, showing no independence.

Instead, Gorbachev stressed the responsibility of the Soviet Union to take due account of West Germans' "position and real weight in Europe and the world at large, while preserving, naturally, their loyalty to their military-political alliances," according to Tass.

Soviet Foreign Ministry spokesman Gennady Gerasimov, at a press conference, described the talks as "frank, constructive and open." West Germany is Moscow's leading western trading partner and serves as an important supplier of machinery and advanced industrial goods, according to analysts here. The Soviet Union is interested in improving economic ties to West Germany, Tass reported.

West German officials here said the two main issues discussed were European security and bilateral economic relations.

Gorbachev and Genscher agreed that "existing treaties," particularly the unratified SALT II agreement and the 1972 antiballistic missile pact, should be observed, Tass said.

Genscher, in a briefing with reporters, said he defended the deployment of NATO missiles in West Germany. "It was quite a serious conversation," Genscher said.

It was unclear whether Washington's draft response to the latest arms proposals Soviet negotiaters made in Geneva last month surfaced in Genscher's morning session with Gorbachev or his afternoon meeting with Foreign Minister Eduard Shevardnadze.