Objective To investigate the rationale of immune privilege of testicular sertoli cell. Methods Testicular sertoli cell was prepared by digested collagenase, trypsin, and Dnase. In vitro, the sertoli cells were culture together with active lymphocytes to observe the effect on killing lymphocytes. SABC was used for labeling the Fas ligand on testicular sertoli cell.Results In vitro, sertoli cell can kill the active lymphocytes, and testicular sertoli cell expresses the Fas ligand. Conclusion Fas ligand expressing on the testicular sertoli cell may be the cause of immune privilege of testicular.