North Carolina Gov. James B. Hunt Jr. concluded yesterday that nine young blacks and a white woman imprisoned following racial disorders in Wilmington, N.C., seven years ago were justly convicted.

But the governor, in a speech televised statewide last night, declared that the 20-to-29-year prison sentences given to the men for firebombing an empty grocery store were too long.

Ending months of pressure on him to intervene, the governor chopped seven to eight years off the sentences making eight of the men eligible for parole later this year, and the ninth, the Rev. Benjamin F. Chavis, a civil rights worker and acknowledged leader of the group, eligible in two years.

The woman, convicted as an accessory, was paroled last year after spending two years in prison.

Hunt was formally petitioned last spring to pardon the 10. However, he declined to intervene at that time, saying he wanted to wait until court appeals were exhausted.

Earlier this month, the 10 lost their last attempt in state courts to overturn their convictions when the Court of Appeals declined to review a lower court judge's decision not to grant a new trial.

Hunt then decided to intervene. He said last week than his action would be "complete, definitive and final."

Whether he will have his way was unclear last night. Some supporters of the Wilmington 10 quickly expressed dissatisfaction with the decision and said they would continue pressing for a pardon or a new trial.

James E. Ferguson II, chief defense lawyer in the case, said Hunt's refusal to pardon the activists "means that North Carolina has firmly rooted itself in the past - in racism and repression." He said Hunt "indicated" that he has "no intention of providing enlightened leadership in the field of reforming the Justice System."

Ferguson has an appeal pending in U.S. District Court here.

The United Church of Christ, which provided bond money and legal fees for the group, said in New York it will continue to back the Wilmington 10. "I am overcome with shock and pain and disappointment," said church President Rev. Avery E. Post.

In his speech, Hunt argued that it is "time for us all now to turn away from the bitterness and rancor of the past, because bitterness and anger and distrust of each other can tear us apart as a state and crush our hopes for the future."

He also contended, without providing specifics, that much of the publicity given to the case has been inaccurate. In recent months he has chastized the national media, saying they disorted some facts in the case and were only presenting one side.

The case has attracted national and international attention, with the 10 defendants being portrayed by many liberal and black political activists as a prime example of Southern racism and justice at its worst.

Amnesty International, a London-based human rights organization, has adopted the 10 as "prisoners of conscience," while at least 50 members of the House - none from North Carolina - have pressed the Justice department to intervene in the case.

Accounts of the controversy have been used by the Soviet press to question President Carter's sincerity on human rights.

But in North Carolina, the debate over the case has sparked sharp divisions along racial and political lines. The case has generated more mail to the governor than any other state issue, with many citizens, most of them white, urging that he keep case figures in jail.

Politicians interpreted Hunt's decision to reduce the sentences as representing a "middle ground." His aides have said that politically the governor faced a "no win" situation at home regardless of what he did. A pardon, they said, would antagonize conservative whites, while declining to intervene would anger black activists. Both camps strongly supported the governor in his 1976 election campaign.

Thus, analysts said, by reducing the sentences, Hunt may not completely satisfy anyone but he may not thoroughly alienate anyone either.

Chavis, 30, coordinator of the Washington, D.C., field office of the United Church of Christ's Commission for Racial Justice at the time of the disturbances, was given the longest sentence, 25 to 29 years. Hunt reduced his sentence to 17 to 21 years, making him eligible for parole in January, 1980. Otherwise he would not have been eligible until mid-1982.

The other eight, all of whom were teenagers at the time of their arrests, had sentences ranging from 20 to 26 years. Their terms were reduced to 13 to 19 years. The first will be eligible for parole on June 1, while the others will be eligible between July and October. Without the reduction they would have been required to remain in jail at least until mid-1980.

The state paroles commission, appointed by the governor, is likely to grant the paroles. All nine have had good records while in custody and none had prior convictions.

In reducing the sentences, Hunt pointed out that the grocery store was unoccupied at the time of the burning. He also said he thought the other crime the nine were convicted of - conspiring to shott at police and fire-fighters who tried to put out the blaze - was more serious than the fire-bombing charge. They were given 3-to-5-year sentences for the conspiracy charge, to run concurrently with the firebombing sentences.