China is increasing its efforts to diplomatically outflank the Soviet Union by arranging a fall tour in which Chinese leader Hua Guofeng will visit the major capitals of Western Europe.

The first foray by a top Chinese leader to Western Europe will almost definitely take him in October to Britain and France, most probably to West Germany and possibly to Italy, diplomatic sources said. Finishing touches are being put on the arrangements in London and Paris.

The tour is viewed as an importan plus for China in its struggle with the Soviets to extend its influence. West Europeans are expected to ignore insistent Soviet pleas that they refuse to sell weapons to China.

China's success in arranging for a diplomatic breakthrough into Western Europe contrasts with the recent failure of the Soviet Union's most controversial ally, Cuba, to schedule a West European tour for its foreign minister this month.

The Cubans are said by European analysts to be eager to erase the aggressive image they have acquired before a major conference of nonaligned nations in Havana next September.

Cuban Foreign Minister Isidoro Malmierva was turned down in efforts to visit West Germany, France, Italy and Sweden*. The French turned him aside by offering him dates they knew to be inconvenient, and no others, sources said. The British say they knew he was fishing for an invitation to London, but that no approach was actually made, perhaps because he had already met so many refusals.

Even though the Cubans, not the Soviets, who are paying the diplomatic price of intervention there.

The only place in the West where the Cubans are having any notable success is Spain, generally recognised as a special case because of Cuba's former colonial ties to Madrid.

Cuban leader Fidel Castro is expected to visit Madrid later this summer. Even the rightist dictatorship of Generalissimo Franco, however, maintained good diplomatic working relations with Castro.

The Soviet Union is too important to West Europeans to be given the cold shoulder, even though it clearly encourages the Cubans to infiltrate regions that are traditional French and British zones of influence in Africa.

The Cubans are currently active in the former French colony of Congo, where Cuban military men are said to be involved in the infiltration of dissidents into the Central African Empire, another former French colony that is a weak link in France's system for alliances in black Africa.

Black Cubans are said to be training opponents of Central African Emperor Bokassa in what may turn into a race between pro-Westerners and pro-Soviets to try to topple him.

When President Valery Giscard d'Estating of France visited the Soviet Union recently, however, diplomatic sources said the French did not complain to the Soviets about Cuban activities in Africa, choosing to accept the official Soviet view that the Cubans act on their own.

The Soviets stressed how unhappy they are about the idea of France selling weapons to China, but the French are understood to have ignored the Soviet warnings.

The French say they are only prepared to sell to Chinese "defensive" weapons, but some inconsistencies in their statements indicate that they have not decided whether they consider advanced figther aircraft "defensive" or "offensive." Such jets are at the top of the shopping list the Chinese are bringing to Britain and France.

West European willingness to receive Hua so soon after the Chinese invasion of Vietnam is striking in a region where public opinion was over-whelmingly sympathetic to Vietnam. French officials say, however, that they tell the Chinese that it is a mistake to launch actions that could threaten the world balance of power or give the Soviets the impression that they are being hemmed in.

The Hua visit to Western Europe is a followup to a tour last August that now appears to have been something of a dry run for the visit to capitalist Europe. Then, Hua called on Yugoslavia and Romania, the most independent Communist nations in the Soviet Union's immediate zone of interest.

The Hua visit to those two "gray-area" states between East and West provoked expressions of Soviet wrath, but this visit to states over which Moscow has even less leverage could make them even more anxious.

The Chinese are obviously no more worried than they were last August, when Hua also visited the shah in Iran, of being accused by the Soviets of consorting with enemies of socialism. CAPTION: Picture, Chinese leader Hua Guofeng is expected to discuss arms purchases in Europe. AP