An investigation on increasing crop output and its mechanism was conducted in four replication in 1988—1989. The crops in the trial were winter wheat and wheatgrass. The irradiation dose of ,60,Co ,γ, rays was 2.5×10,4,Gy. The experimental result showed that the dry matter, N content of stalk and leaves above ground of wheatgrass and kernels yield of winter wheat had a considerable increase of 86.49%, 38.68% and 48.41% respectively after soil irradiation. The A,N, value of soil was from 1616.8 mg before irradiation to 5112.8 mg after irradiation, and ,15,N aboundance of stalk and leaves of wheatgrass in irradiated soil had decrease of 50.45% comparing with unirradiated soil. The content of nutrient elements in soil before and after irradiation was assaied. The availble N, P, K and Mn had an increase of 21.30%, 30.75%, -10.79% and 46.97% respectively after irradiation. The organic matter content, pH value and radioactivity in the soil before and after irradiation had no significant changes.