Although the spotlight was on Chinese President Li Xiannian during his visit to Washington, China analysts have been paying close attention to two rising political figures accompanying him.

The person U.S. officials and analysts are scrutinizing most carefully is the delegation's No. 2, Vice Premier Li Peng. At 56, he is considered the most likely candidate to become China's next premier.

The other is Wang Zhaoguo, who, at 44, has catapulted from deputy director of an automobile factory to a chief of staff position in the Communist Party with duties similar to that of a Donald T. Regan, according to China experts.

For Li and Wang, this visit to the United States is a first. "They [Chinese leaders] are clearly grooming these guys to give them more exposure," said Harry Harding, a China scholar at the Brookings Institution.

Chinese leaders often have a "narrow, ideological" view of the United States, and the country's "visual impact" will be important as the delegation, which leaves Washington today, travels westward to other U.S. cities, said Parris Chang, a political science professor at Pennsylvania State University.

U.S. officials need to get to know the two leaders, Chang said, "because these are the people they are going to be dealing with for quite some time, whether it is during the Reagan administration or the next administration."

An indication of Li Peng's importance was the signing Tuesday of the long-stalled nuclear technology agreement. As one of the architects of China's nuclear-power program, Li has taken a strong interest in the agreement. U.S. officials said Li, an engineer, showed "a surprising grasp of detail" even though he was not directly involved in the negotiations.

During the delegation's visit here, Li conducted meetings separately from the president, including sessions yesterday with Charles Z. Wick, director of the U.S. Information Agency, and Vice President Bush. According to a spokesman for Bush, the two met for 45 minutes and discussed "a full range of economic and trade issues."

One State Department official said Li appeared to U.S. officials to be a "very sharp, very articulate guy who has the tendency to go right to the heart of the issue."

In recent months, Li's responsibilities have increased. Besides the energy and transportation industries, he is also in charge of the electronics industry. When the education sector was reorganized last month, he became the head of the new State Education Commission.

According to some analysts, Li also appears to be gaining a foreign policy role. Educated in the Soviet Union, Li was sent to Moscow in March to attend the funeral of Konstantin Chernenko and reportedly conversed with Soviet leader Mikhail Gorbachev without the help of an interpreter.

He became the highest-ranking Chinese official to visit East Germany, Poland and Hungary in more than 20 years when he made a 17-day trip in May, during which China signed five-year trade pacts with the three countries.

Li Peng is from the same province as China's paramount leader, Deng Xiaoping, and has longstanding ties to current and former Chinese Communist Party leaders. The son of a communist revolutionary hero, Li was orphaned at 3 and was later adopted by the late premier Chou En-lai and his wife, Deng Yingchao. Li's wife, two sons and one daughter also work in China's power industry and are sometimes referred to in the official Chinese press as "a family of power specialists."

Li also has a reputation for modesty; he apparently has won approval from many ordinary people for refusing to move into the superior housing available to officials of his rank.

Less well known is Wang, a protege of Deng. Wang, a graduate of Harbin Engineering University, which has been called China's MIT, has also been exposed to things American. He is a graduate of a pilot business management training program in the northern port city of Dalian that is modeled on those in the West.

"Right now, he's . . . a briefcase carrier. He needs to establish his credentials. But he is on the verge of power," said one analyst.

Said Penn State's Chang: "One cannot play down the importance of Wang because age is in his favor. In his position as director of the staff office of the Communist Party's Central Committee, in time, he will develop himself into a generalist, and that is very important for China."

At a special party conference this fall, Wang is expected to be among several named to the Politburo in a reshuffle of the top leadership.

Wang apparently came to Deng's attention in July 1980, when the youthful technician was introduced as the newly promoted deputy director of Hubei Province's No. 2 automobile factory.

Deng was told of Wang's reforms that set up an aggressive sales force and upgraded services that led to a tripling in the company's revenues, despite accusations that Wang was a "capitalist roader."

Wang was subsequently named to head the 48 million-member Communist Youth League. Last year, he was named director of the general office of the party's secretariat, the group that meets frequently to make policy decisions.