To study the influence of radiation on osteoblasts and osteoclasts in vitro. ,137,Cs γ rays was used to irradiate the rat calvaria — derived osteoblasts and femur — derived osteoclasts. The changes in morphology, proliferation rate,ALP activity,mineralized nodules forming capacity and osteocalcin mRNA levels of irradiated—osteoblasts and osteoclastic apoptosis rate were detected respectively. Degenerative changes in morphology was observed and the inhibitory effects on osteoblasts proliferation rate by radiation was correlated with dose and ALP activity was also decreased by 28%. The nodules numbers was increased by 91.75% in lower—dose(0.5—1Gy) and decreased by 67.13% in higher — dose (6Gy). Osteocalcin transcription levels were 1.46 in 6Gy and 2. 75 in control. The osteoclastic apoptosis rate was increased with irradiation dose. Low —dosage γ irradiation may accelerate the aging process of osteoblasts and induce osteoclasts apoptosis in vitro.