Taiwan's best-known dissident, an academic who has led a life colorful enough for a soldier of fortune, is going home today after 22 years of political exile in the United States.

The return of Professor Peng Ming-min, who escaped in 1970 from Taiwan - then as closed to political dissent as China is today - is likely to add more spice to the island's already contentious legislative election in December.

At the time he fled, Peng was under a sentence of house arrest for life for advocating democratic government and independence from China.

The Nationalist government that jailed him still rules Taiwan. The government's gradual liberalization of political life has made it possible for Peng to return and advocate causes that once landed him in trouble.

Both the Nationalist government on Taiwan and the Communists in Beijing insist that Taiwan and China are two parts of the same country and must someday be reunited - a proposition many Taiwanese consider impractical and potentially hazardous.

The question of whether Taiwan should declare itself independent of China, a status it enjoys in all but name, has been made a major issue by the opposition Democratic Progressive Party.

EARLY ALLY OF CHIANG'S

China periodically renews its long-standing threat to invade the island if Taiwan declares its independence. That threat has been reinforced by China's purchase of advanced aircraft and other weapons from Russia and President Bush's decision to sell Taiwan 110 F-16 fighters.

"So this election is very important from any point of view, whether of democracy, power or independence," Peng said in an interview in Seattle earlier this month before a fund-raising dinner attended by more than 140 local Taiwanese.

A U.S. bombing raid on Tokyo cost Peng his left arm while he was a student there during World War II. Not long thereafter, he witnessed the flash of the atomic bomb that destroyed Nagasaki.

As the war ended, Japan withdrew from Taiwan, which it had controlled since the turn of the century - only to be followed in 1947 by the remnants of Chiang Kai-shek's Nationalist army and government, which began arriving on the island as Mao Tse-tung's Communist revolution swept across China.

Chiang initially favored Peng and appointed him an adviser to the Republic of China's United Nations delegation. But gradually, Peng says, he became disenchanted with Chiang's authoritarian government and the realization that without change the people of Taiwan would have no direct say in the island's future.

ESCAPED TAIWAN IN 1970

In 1964, when he was head of the political-science department at National Taiwan University, Peng decided to speak out and drafted what amounted to a call for total independence from China and for representative government.

Peng was arrested and sentenced to eight years in prison, which after 14 months was commuted to house arrest for life. In 1970, he managed to escape and was granted political asylum in Sweden and shortly thereafter permanent-resident status in the U.S.

He taught at the University of Michigan and Wright State University in Ohio. In recent years, Peng has been living in Lincoln City, Ore., where he is head of the Asian-Pacific Council on Democracy, a private foundation.

Peng's return was made possible earlier this year, when the Nationalist government lifted his sentence and reduced a "blacklist" of government opponents not allowed to enter the country to a handful of people who allegedly engaged in violence against the government.

PLANS ROLE IN ELECTION

Peng said he plans to speak out for full democracy and independence for Taiwan in an attempt to assist candidates in this fall's elections who share his views. He said, however, that he intends to avoid endorsing individual candidates.

Wu Li-pei, chairman and president of GBC Bancorp in Los Angeles, who is organizing the logistics of Peng's return, said he would be accompanied by some 65 other Taiwanese living in the U.S. and joined by another 35 or 40 in Hong Kong.

A major political rally is scheduled at the Taipei airport to mark his arrival Sunday.