The aim of this study is to evaluate the effect of immobilization at different angles on the mechanical properties of rabbit Achilles tendon. The left hindlegs were immobilized with knee in extension, ankle either in extension or plantar flexion 90°. After 4 weeks, the exponential functions, stress-strain curves of Achilles tendon were compared between different groups. The results showed that compared with normal group, the stress-strain curves and material constants of Achilles,tendon were different significantly in either immobilized-I group or immobilized-Ⅱ group, but there were no significant difference between these two immobilized groups. From these findings, we concluded that static stress could not prevent the changes of mechanical properties of Achilles tendon induced by immobilization.