Objective To study the role of WIP1 gene in mouse B cell and T cell development． Methods The proportion of the B cell in bone marrow and T cell in the thymus were determined by the flow cytometry． Results Although the proportion of different subsets in B cell development was normal，the total number of B cell in bone number was decreased． WIP1 gene knockout mice had defect in thymus development，the proportion of CD8 /CD4 double negative cells was increased，but the CD8 /CD4 double positive cells was decreased． Conclusion WIP1 gene plays an important role in the development of B cell and T cell．