Humans in Space suffer from microgravity-induced muscle atrophy and attenuated bone strength. High-frequency, low-amplitude vibration has been proposed as a treatment to prevent bone loss and the decrease in strength of bone. In this study,the effect of vibration on countering microgravity-induced bone loss was investigated.15 SD rats were divided into three groups(n=5, each): tail-suspension(TS), TS plus45 Hz(0.3 g) vibration exercise(TSV), and control(CON). Tail-suspension was to unload rat hindlimbs and a device was developed by our group, with which the rats were trained by vibration twice per day on hindlimbs during tail-suspension. After 21 d, bone mineral density(BMD) was measured by micro-CT and porosity by combining EXAKT and Olympus BX51 in tibia. The results showed that trabecular BMD was significantly decreased and cortical porosity increased in TS compared with CON, while there was no significantly difference between TSV and CON. These suggest that vibration exercise could prevent bone attenuation induced by simulated weightlessness and it is possible to be as a countermeasure of microgravity-induced osteoporosis. Humans in Space suffer from microgravity-induced muscle atrophy and attenuated bone strength. High-frequency, low-amplitude vibration has been proposed as a treatment to prevent bone loss and the decrease in strength of bone. In this study, the effect of vibration on countering microgravity-induced bone loss was.15.15 SD rats were divided into three groups (n = 5, each): tail-suspension (TS), TS plus 45 Hz Tail-suspension was to unload rat hindlimbs and a device was developed by our group, with the rats were trained by vibration twice per day on hindlimbs during tail-suspension. After 21 d, bone mineral density (BMD) was measured by micro -CT and porosity by combining EXAKT and Olympus BX51 in tibia. The results showed that trabecular BMD was significantly decreased and cortical porosity increased in TS compared with CON, while there was no significant difference between TSV and CON. These suggest that vibration exercise could prevent bone attenuation induced by simulated weightlessness and it is possible to be as a countermeasure of microgravity-induced osteoporosis.