Abstract: Using in situ hybridization technique with Dig Labeled DNA probe,the expression of Si1 gene in testis of one-day old,3 weeks old and mature Kunming mice were studied.At the same time,TUNEL method were used for detection of apoptotic cells in situ to detect the cell apoptosis of the spermatogenic cells in testis of mice at 15th day after birth,20th day after birth and 25th day after birth.The results are as follows:(1)The expression of Si1 gene was very strong in partial seminiferous tube of 3 weeks old mice,but the expression of Si-1 gene was not be observed in testis of one-day old mice and mature mice.(2)The number of apoptotic cells increased from 15th day after birth to 20th day after birth,reached its peaks on postnatal 20th day and descended on 25th day after birth.So the conclusion that Si1 gene participates in the development of testis of mice,and the period of Si-1 gene expression and the cell apoptosis of the spermatogenic cells in mice were synchronously get.