Background: Spermatogenesis is a programmed route of germ cell proliferation and differentiation that could produce abundant numbers of spermatozoa. The antioxidants play a vital role in decreasing ROS production in cells, therefore plants extract administration with antioxidant property can prevent of cell damage. In the present study, antioxidant effects of Calligonum extract on proliferation and colonization rate of spermatogonial cells was assessed. Materials and Methods: After isolation and culture of spermatogonial stem cells (SSCs) from neonatal mice (4-5 day old) and identification by PLZF and Oct4 markers, the therapeutic effect of Calligonum comosum extract was measured on the cells treated with H2O2. Induced oxidative stress cells were treated with 10 μg/ml extract for 3 weeks. ROS levels were assessed by flow cytometry, proliferation by cell count and TAC by FRAP assay. Also, the apoptosis rate was measured with P53 and Bax genes by real time PCR method. Results: After three weeks of treatment, the Calligonum group showed significantly lower ROS level relative to the H2O2 group. Antioxidants levels were in Calligonum group significantly higher than the H2O2 group (P≤0.05). There was a strong inverse relationship between the two groups. Proliferation and colonization rate were in Calligonum + H2O2 group significantly higher than H2O2 group alone (P≤0.05). Finally, the results of the study indicated that P53 and Bax expression decreased in Calligonum + H2O2 group compared to H2O2 group. Conclusion: The results of present study expressed that Calligonum as a plant with antioxidant effect could reduce the level ofROS, and increase proliferation and colonization rate and TAC. In other hand, 30 μM doses of H2O2increased oxidative stress and apoptosiswhile decreased proliferation of SSCs.