Eleven Iranian "terrorists" convicted of Communist affiliations last month began a series of personal pleas for leniency before a military appeals court today.

The proceedings, which have been opened to foreign journalists and the public, are widely viewed as an attempt by Iran to improve its human-rights image abroad. U.S. Secretary of State Cyrus R. Vance is scheduled to arrive here Friday.

The 11, one woman and 10 men, including an army officer, pleaded guilty last month to charges that they belonged to the "revolutionary wing" of the outlawed Iranian Tudeh (Communist) Party. They also admitted links with eight alleged terrorists killed in a shootout with police last Christmas.

All of the accused have foreign university degrees and were sentenced April 12, after what critics called a "show trial," to prison terms ranging from life to three years.

Their appeal session began yesterday with the military prosecutor demanding life sentences for the eight defendants who did not receive the maximum punishment.

The proceedings had all the appearance of being staged, as five defendants mechanically read confessions they had hand-written on government letterhead paper. In their appeals they praised Shah Mohammed Reza Pahlavi and blamed their alleged subversive activities on corrupting foreign influences. They asked for reduced sentences.

A relative of one of the defendants, interviewed during a recess, expressed confidence that the sentences would be reduced or commuted by the shah. When asked if the outcome had been arranged beforehand, the relative hesitated and replied nervously, "I don't know."

The 11 have said they were well-treated. The appeal hearing is expected to be concluded before Vance arrives late Thursday for a three-day visit. During his trip, Vance will confer with the shah and attend a meeting of the Central Treaty Organization.

In today's appeals, two defendants, both 40-year-old executives who drew life sentences, confessed that they had received guerrilla training in China.They said they abandoned their plan to provoke a peasant revolution in Iran after they returned and saw what they said was the shah's success in combatting feudalism and ridding the country of foreign domination.

None of the defendants was charged with any actual terrorist actions in Iran.

Another appellant, Abbas Malekzadeh Milani, 29, who earlier, drew a 12-year prison sentence, struck a nationalistic note in his plea.

"I left the country when Iran still had no political independence and was being exploited" said Milani, holder of a docterate from the University of California, "loved my country and wanted to change this bad situations."

Milani, a First Lieutenant in the army, was performing compulsory military service as a university lecturer in Tehran when he was arrested late last year. He confessed, that he had joined the confederation of Iranian Students, a leftist grouping of dissident Iranians studying abroad.

Four steel-helmeted soldiers stood guard with sub-machine guns inside the courtroom as about 30 spectators most of them relatives, silently watched the proceedings.

Outside the building two truckloads of armed soldiers waited in the landscaped military compound, near Tehran's Qasr Prison.

Periodically, the spectators and defendants cast sideward glances at a press gallery where four foreign correspondents covering the rare public trial were seated.