Objective: To determine the roles of Pumilio family in the postnatal development, we established the Pumilio1/Pumilio2 (Pum1 and Pum2) inducible knockout mouse model. Methods: Pum1 flox/flox;Pum2 -/- mice were mated with R26-ERT2Cre/Cre mice to obtain R26-ERT2Cre /+;Pum1 flox/flox;Pum2 -/- mice. The experiment group (three weeks old mice and adult mice) was injected with tamoxifen, while the control group was injected with the same amount of peanut oil. The knockout efficiency of Pum1 at DNA, RNA and protein levels of multiple organs in mice was determined. The histology of the testis as well as cell proliferation and apoptosis of the testicular cells were examined. Results: The Pumilio1 RNA and protein of thymus and testis were knocked down significantly. The knock down efficiency of Pum1 varies from tissues to tissues but reaching a minimum of 50%. The mouse model of Pum1 and Pum2 gene induced knockout was successfully constructed. The weight of thymus, spleen and testis of male mice in the 3-week experiment group decreased significantly, supporting the critical role of PUM in postnatal organ growth.. The hematoxylin and eosin (HE), TUNEL and BrdU staining of testis pathology showed disrupted spermatogenesis, increased apoptosis and decreased proliferation of spermatogenic cells in 3 weeks experiment group testis. Although, the Pum1 of each organ in adult group was knocked down at different levels, the spermatogenesis of adult experimental group was not significantly affected. Conclusion: The inducible knockout of Pumilio family genes in the postnatal 3 weeks mice can lead to the weight loss of related organs. The inducible knock down of Pumilio gene in the testis may lead to testis weight reduction and disrupted spermatogenic process with increasing the apoptosis and decreasing proliferation of spermatogenic cells. Hence this inducible PUM knockout model provides a new tool to study the roles of PUM in postnatal and adult mice, and supports the future development of PUM as potential drug targets for diseases involving PUM-mediated translational control.