Under the simulated microgravity, the microtubulin content and the alkaline phosphatase activity of cultured chicken embryonic chondrocytes reduced remarkably, which indicated that the simulated microgravity induced the changes of microtublar system and the calcification of chondrocytes. The antagonistic effects of Mg²⁺ and SeO₃^2- against the changes were studied. The results showed that these changes can be partly antagonized by 1 mg/L Na₂SeO₃ and completely antagonized by 5 mmol/L Mg²⁺.