The Reagan administration has quickened the pace of its diplomacy toward southern Africa, sending senior emissaries to meet key actors in the long-running Namibian drama, including the dispatch of Gen. Vernon Walters to see Angola's leaders.

The State Department said yesterday that a meeting with a Namibian guerrilla leader in Europe with Assistant Secretary of State Chester A. Crocker and an unannounced tour of southern African capitals by Walters and Deputy Assistant Secretary of State Frank G. Wisner II are part of an effort to move forward "on an urgent basis" toward a settlement of the Namibian issue.

Independence from South Africa for Namibia has been a high-priority issue for African states, and is closely related to the question of Cuban troops in Angola, a high-priority issue for Washington.

U.S. sources said the flurry of activity, to be continued in another series of senior diplomatic visits to Africa next week, reflects a judgment that South Africa and black African "front-line" states are ready to move toward breaking the logjam over the future of Namibia, a mineral-rich territory formerly called South-West Africa.

There were also signs of growing optimism that Angola, which has been engaged in improving its relations with western countries since late last year, will agree to send many or most of the Cuban troops home in the context of a regional arrangement involving Namibia and other threats to its security.

There was no indication that Walters, the multilingual special U.S. emissary and veteran of confidential missions, can complete a deal with the Angolans.

However, his presence in the Angolan capital of Luanda, along with his visits to Presidents Julius Nyerere of Tanzania and Kenneth Kaunda of Zambia, both respected African leaders, is likely to generate a stir in Africa.

Walters' mission, like that of Crocker in Bonn with Sam Nujoma, leader of the South-West Africa People's Organization (SWAPO), is intended to dispel suspicions and exchange ideas on early movement toward a Namibian solution, according to State Department officials.

The Namibian settlement was set back earlier this year when Nujoma's guerrilla organization rejected a plan for voting in post-independence Namibian elections.

Nujoma's meetings in Bonn with Crocker and his host, West German Foreign Minister Hans-Dietrich Genscher, reportedly prepared the ground for solving or temporarily bypassing the voting issue and moving on to such issues as military authority during the transition to independence.

Nujoma reportedly told a news conference in Bonn yesterday that he was encouraged by his meeting with Crocker and that the United States and the four other nations of the western "contact group" on Namibia was changing its procedures to speed a settlement.

Diplomatic sources added that Nujoma had agreed to an "understanding" or "commitment" that his country would remain nonaligned if he gained power after independence.

A State Department official familiar with the Bonn talks called them "productive," and expressed hope that they will lead to positive results.

The South African end of the Namibian diplomacy was facilitated by the arrival here last week of Brand Fourie, the top career official of the South African Foreign Ministry and a 30-year veteran of Namibia diplomacy, as new ambassador to the United States. Fourie has yet to present his credentials, but is already deep in talks with U.S. officials.

Walters' planned talks in Angola later this week follow a series of meetings between Crocker and Angolan Foreign Minister Paulo Jorge in Paris and Luanda in January, March and early April.

On March 24, in an unusual gesture of conciliation toward Angola, which Secretary of State Alexander M. Haig Jr. previously had called a "Soviet surrogate," a reception was held at the State Department for Dr. Jose Victor de Carvalho, governor of the Angolan Central Bank, who was visiting Washington under private sponsorship.

Walters began his African tour in Kenya, and will visit Malawi in addition to his other stops, U.S. officials said.