Hu Yaobang, China's Communist Party chief, begins a visit to Western Europe today aimed in part at convincing Europeans that China's economic changes are here to stay.

China, Hu will argue, is safe for European business investments. But Hu's second major aim, according to observers here, is to add to his credentials as the successor to Deng Xiaoping, China's senior leader.

Hu's four-day visit to Britain will be only his second to a western nation. He has previously traveled to Australia.

At some point within the next few years, Hu, 71, is supposed to take over as the head of a collective leadership. Deng, 81, has been talking about retiring for some time. He claims to have turned over day-to-day affairs to Hu and his colleagues. But Deng clearly still has the final say in many important matters.

One of the major questions facing western diplomats and investors here is whether Hu has the strength and standing to hold China together and keep Deng's economic reforms moving.

One concern of western observers is that Hu does not share Deng's strong military background and thus might have trouble keeping the Army in line. Another concern is that Hu has a tendency to shoot from the hip. But while Hu's inclination to speak his mind, on occasion with jarring candor, might disturb some Chinese, it could serve him well in the West, where candor is often appreciated.

On his trip to Australia in April last year, Hu, like Deng a diminutive chain smoker, came across as outgoing and colorful. He is now to visit Britain, West Germany, France and Italy, returning June 23.

China in recent years has stressed strong support for a united Western Europe as a stabilizing force in the face of superpower rivalry. Li Peng, a vice premier accompanying Hu, last week praised the Eureka plan for high-technology cooperation among West European nations. China apparently hopes that the plan will facilitate the transfer of European technology.

Trade between China and Britain came to more than $1.4 billion last year, according to Chinese officials. But in an interview with Radio Peking, British Foreign Secretary Geoffrey Howe said that while this trade was substantial, "it should be a great deal more substantial."

China's largest West European trading partner is West Germany, with last year's two-way total put at $3 billion. China's trade with Italy last year was valued at $1.15 billion and with France $830 million.

Hu is in a position to assure the Europeans that he will initiate no major departures from policies set by Deng. The two have worked closely for more than four decades, with Deng always in the senior position. In the 1940s, they served in the Army together. When Deng was ousted from power in the 1960s and again in 1976, Hu also was purged.