Objective To elucidate the developmental process of spermatogenic cells in immature Cynomolgus monkey. Method Testis of 0，0. 5，1，1. 5，2，2. 5，3，3. 5，4 years old Cynomolgus monkeys were collected，paraffin sections were made，stained with HE and PAS /H ( pexiodic acid-schiff / hematoxylin，PAS /H) . Based on the staining pattern，the developental process of spermatogenic cells in immature Cynomolgus monkey was analysed and spermatogonial stem cells were primarily identified. Result HE Staining showed spermato gonial stem cells ( including dark type A spermatogonia，transitional type A spermatogonia and pale type A spermatogonia) were the only spermatogenic cells in seminiferous epithelium of Cynomolgus monkey at 1 year old and below，Type B spermatogonia emerged at 1. 5 years old，spermatocyte emerged at 3 years old，and all types of spermatogenic cells ( from spermatogonial stem cells to sperm) were present at 4 years old Cynomolgus monkey. PAS /H staining showed cytoplast of dark type A spermatogonia as positive，transitional type A spermatogonia as weakly positive，and pale type A spermatogonia as negative，while cytoplast of sertoli cells and other spermato genic cells as negative in Cynomolgus monkey between one year old and 2. 5 years old. Cytoplast of spermatogenic cells have a different PAS /H staining pattern in Cynomolgus monkey at 6 months old and below，3 years old and above. Conclusion This article detailedly elucidated the progressive development model of spermatogenic cells with age and established a new method for in situ identification spermatogonial stem cells in immature Cynomolgus monkey. These results will lay the foundation of spermatogonial stem cells related research in Cynomolgus monkey.