A D.C. Superior Court jury yesterday awarded $225,000 to two Lorton Reformatory inmates who sued the D.C. Department of Corrections after they were seriously injured in an April 1980 assault by two other inmates.

The jury awarded $125,000 to Nathaniel Parker, 37, who is serving a life sentence for murder and is still in the facility. It awarded $100,000 to Walter Ferguson, 40, who is serving a six-year sentence for carrying a pistol without a license and making false statements under oath. Ferguson now is in a federal penitentiary.

Both men were sitting in their dormitory in the medium security facility when they were attacked by two men wearing ski masks, according to Lawrence H. Schwartz, Ferguson's attorney. No motive for the attack was ever determined, Schwartz said, and no charges brought against any other inmates. Schwartz said Parker was stabbed in the liver and thigh and Ferguson was slashed several times in the head.

In their suit, Parker and Ferguson said that Lorton officials mixed known dangerous inmates and less dangerous ones, and did not properly supervise them. They also claimed Lorton did not adequately inspect prisoners and the facility to confiscate weapons, such as the two-foot-long homemade knives allegedly used in the attack.