Jiang Qing, the defiant widow of Mao Tse-tung who had been sentenced to die for persecuting thousands of Chinese during the Cultural Revolution, was spared from the firing squad today and condemned to life imprisonment.

Jiang, 69, whose 1981 death sentence had been set aside for two years to give her time for self-reproach, was found by court review to have "not resisted reform in a flagrant way," Chinese radio reported tonight.

Foreign analysts said the judicial ruling seemed artfully constructed to justify the politically expedient reprieve without suggesting she had truly repented.

According to Chinese criminal law, death-row prisoners who demonstrate "sufficient repentance" during a reprieve can have their sentences commmuted to life prison terms.

Far from remorseful during her 1980 show trial, the Cultural Revolution's first lady openly mocked the solemn proceedings, spouting radical epithets and deriding Mao's moderate successors as "revisionists."

Two years' reprieve reportedly had little impact on the one-time Shanghai film starlet turned political hatchet man. As late as August, Communist Party General Secretary Hu Yaobang told foreign journalists, "Jiang Qing lives well in her prison but persists in behaving like an enemy of our people politically and ideologically."

Her reprieve, however, is believed never to have been in doubt by the current regime, which apparently regards her less dangerous as an imprisoned enemy than as a martyr whose execution couuld trigger a backlash from latent leftists.

The Supreme People's Court also commuted the death sentence of one of Jiang's radical confederates, Zhang Chunqiao, 65, a former party vice chairman, who showed his disdain for the 1980 trial by refusing to utter a single word.

Broadcast nationwide by the state-run radio, the reprieves close the bloodiest chapter in Chinese Communist history. From 1966 to 1976, Red Guard terrorists inspired by Mao destroyed everything smacking of "bourgeois" lifestyle or China's Confucian past. They harassed, beat and killed anyone suspected of revolutionary infidelity, including many of today's top leaders.

Official estimates of the human cost are staggering--100 million are said to have suffered from the reign of terror. Prosecutors assembling evidence against Jiang and her associates confined themselves to cases they could document: 34,000 deaths and more than 700,000 persecutions.

Jiang, who as cultural czar and Mao's helpmate was held responsible for much of the suffering, insisted throughout the trial that she had merely acted on behalf of her husband.

"I was Chairman Mao's dog," she asserted. "Whomever he told me to bite, I bit."

Her courtroom outbursts were the only spontaneous moments in the stage-managed hearings that were televised nightly to a Chinese public seeking catharsis for the brutal era. She regularly defied and cursed the judges, laughed off charges against her and vilified state witnesses as "traitors and bastards."

Even at her sentencing, she had to be bodily evicted in handcuffs, struggling with four bailiffs as she shouted, "To rebel is justified!"

Tonight's brief, almost anticlimactic announcement was a reminder of how much political life has stabilized since the trial, when it took the ruling Politburo a month of reportedly stormy debates to weigh the consequences of sentencing the widow of Communist China's founding father.

Her defense forced party leaders to conduct their first public evaluation of Mao, which they had been gingerly sidestepping for fear of arousing his ultraleftist followers still prominent in party circles.

Since then, the regime headed by Deng Xiaoping has steered the party into reassessing Mao as a brilliant but flawed leader who made serious mistakes in his final years; it has ousted Mao's handpicked successor and replaced him with Deng's protege; it has managed the election of a new Central Committee and Politburo cut in Deng's pragmatic mold; and it has dismantled many of Mao's pet projects, including communes.

With its growing confidence and power, Deng's ruling faction has begun mopping up Cultural Revolution remnants in the provinces--33 leftists have received long prison terms since August--and is gearing up for a new, three-year party purge aimed at Maoist holdovers.

Jiang and her three closest cronies, collectively known as the "Gang of Four," are the scapegoats for all China's ills. In addition to Jiang and Zhang, the other two one-time Politburo leaders--Yao Wenyuan and Wang Hongwen--are serving terms of 20 years and life, respectively.

Jiang, who married Mao in the 1930s in the Communists' mountain stronghold of Yenan, stayed on the fringes of national politics until the mid-1960s. Then Mao, looking for a way to inject radical fervor into Chinese life, put her in charge of purifying the arts.

Soon she was running the military's cultural affairs and using her position as a forum for unleashing the youthful Red Guard zealots.

Among specific charges at her trial, Jiang was accused of framing Deng, who was purged twice during the chaotic decade, and directing brutal "struggle sessions" against the late president, Liu Shaoqi, who finally died in prison from the abuse.

Today's commutation is certain to be unpopular with millions of Chinese who lost jobs, homes, health and dignity during the Cultural Revolution. It is expected to be even harder to swallow because of the recent executions of Chinese officials for such victimless crimes as embezzling $30,000 from the state.

At her trial, Jiang repeatedly dared the judges to order her shot in broad daylight in Tiananmen Square below the beaming portrait of Mao.

When she was warned that her courtroom slanders and outbursts constituted a new crime of contempt to be considered against her at sentencing, she replied defiantly, invoking a Chinese fairy tale character who had the magic power to create new monkeys with a wave of his hand: "Just ask the monkey king to give me more heads to be cut off."