Objective To observe the cleavage effect of Caspase-3 on PIAS1 protein in vitro. Methods PIAS1 protein was expressed in HEK293T cells. Co-immunoprecipitation (Co-IP) was used to observe the binding between PIAS1 protein and Caspase-3. The cleavage effect of Caspase-3 on PIAS-1 protein was detected by in vitro proteolytic cleavage test. Results Co-IP result showed that Caspase-3 bond to PIAS1 in vitro. Proteolytic cleavage test showed that PIAS1 was cleaved by active Caspase-3. Conclusion It has been shown that Caspase-3 can interact with PIAS1 protein in vitro, and PIAS1 can be cleaved by Caspase-3 in vitro.