Objective To investigate the effect of stretch in different frequencies on histologic appearance and expressions of typeⅠand type Ⅲ collagen protein in Achilles tendons of rabbits, so as to explore the relationship between stretch frequency and tendinopathy. Methods Fourty-five male New Zealand white rabbits were randomly divided into 3 groups, one was control group without electrical stimulus and the other two groups were electrically stimulated to drag Achilles tendon in the frequencies of 0.17 and 1 Hz, repetitively. The histologic appearance was observed under light microscopic, and expressions of typeⅠand type Ⅲ collagen protein were measured by immunohistochemistry staining. Results After 4 weeks of stretch, the expression of type Ⅰ collagen protein decreased, while the expression of type Ⅲ collagen protein increased, but total collagen protein expression decreased. After 6 weeks of stretch, Achilles tendon tissues presented typical tendinopathy in histology in 1 Hz group, and the expression of type Ⅰ collagen protein increased, while the expression of type Ⅲ collagen protein had no change in 0.17 Hz group. Conclusions High-frequency stretch results in tendinopathy in Achilles tendon, while low-frequency stretch may play a role in its repair.