Objective: To identify the interaction between protein PTHrP and Bmi-1, and to further explore the underlying signaling pathway of PTHrP. Methods: The PTHrP gene was amplified by RT-PCR and inserted into corresponding sites of expression vector pGEX-2TK, and the fusion protein expressed in E.coli BL21 induced by IPTG. After identifying, the interactions between protein PTHrP and Bmi-1 were characterized by GST pull-down assay and Western Blot. Results:The new recombinant expression vector pGEX-2TK/mPTHrP was constructed and expressed successfully our. experiment confirmed the interactions between the protein PTHrP and Bmi-1. Conclusion:PTHrP specifically interacted with Bmi-1, which may modulate PTHrP downstream signaling pathway.