The assassination of President Park Chung Hee was the product of a small, hastily improvised plot, according to testimony unfolding at the trial of his alleged assassin here.

The plot, the testimony indicates, was directed by a man who fancied himself a liberal democrat destined to slay the country's despotic ruler.

This picture has emerged over three days in the tightly controlled military trial of the accused slayer and seven other men. Testimony has produced no evidence of a wider conspiracy and it has largely followed the lines of the assassin's alleged confession that was disclosed by military leaders in the week after the Oct. 26 slaying.

It tends to pin the blame directly on former Korean Central Intelligence Agency Director Kim Jae Kyu, and depicts the others as accomplices under his command.

Officers of the court-martial have insisted on close control. News reports of the proceedings are subject to censorship and potentially inflammatory language is ordered deleted.

Defense attorneys' request for more leeway in bringing out evidence are routinely turned down. When one defendant is testifying, the other seven are removed from the courtroom so they cannot hear what is said about them.

Kim already had allegedly confessed to shooting Park and Park's chief bodyguard at a dinner while five of his assistants were shooting the president's other bodyguards in adjoining rooms and outside the KCIA headquarters.

The only new element to emerge is Kim's self-portrait, given in testimony Saturday. He said he had become disenchanted as early as 1972 with Park's "Yushing" Constitution and by 1974 was considering killing him.

On two occasions, in 1974 and 1975, he said he had carried a pistol during meetings with the president, in one instance concealing the weapon behind a national flag.

In the version previously revealed by martial law authorities, Kim had first plotted an assassination last summer and had finally acted only when he feared he was about to be removed from the KCIA leadership because he had lost the president's trust.

Kim described himself to the military court as a liberal democrat who believed the constitution had been imposed merely to advance Park's self-interest.

The testimony so far has not deeply incriminated the late president's chief secretary, Kim Kae Won. He is a friend of the accused assassin who was in the dining room on the fatal night and escaped unscathed.

Kim Jae Kyu said the secretary had no advance notice of the assassination plan and he volunteered that he would probably have killed Kim Kae Won along with the others if the secretary had raised any objections during the shooting.

Kim Kae Won testified this morning that he knew nothing of an assassination plot before he went to the fatal dinner with the president.

The testimony offers no new insights into the role of Army Chief of Staff Chung Sung Hawa, who was in a nearby restaurant at the time of the killing. His presence there and his actions after the shots rang out have been major points of interest in the case.

Kim Jae Kyu said he had invited the general to meet him for dinner that night so that he would be nearby and easily contacted after the assassination. The accused killer said he planned to have the general "control the situation" under martial law until he had time to establish a "revolutionary committee" to take control of the country.

Gen. Chung is in charge of the martial law command, which has maintained order since the assassination and which was in overall charge of the investigation and prosecution of Kim Jae Kyu and the others.

Each morning as the trial begins, the defendants are brought into the military courtrom in handcuffs. Kim Jae Kyu and Kim Kae Won are dressed in traditional Korean clothes, including white shoes and jackets. Five others are clad in prison uniforms and one, an Army colonel who served on the KCIA director's staff, wears army fatigues.

Kim Jae Kyu, 53, is being represented by a battery of 21 defense attorneys, some of whom in the past had defended dissidents accused of violating laws and proclamations prohibiting dissent.

They are representing him without charge, even though the military command has made public information showing that Kim Jae Kyu had become a wealthy man during his career as army general, construction minister, and KCIA director.

Kim Jae Kyu, Kim Kae Won, and five of the KCIA aides are charged with the capital offenses of murder, attempted murder and attempted sedition. The eighth defendant, also a KCIA employe, is accused of destroying evidence.