Objective To prepare a polycaprolactone (PCL) composite scaffold which can slowly release bone morphogenetic protein 2 (BMP-2) for a long time, and to explore the application value of PCL composite scaffold in bone tissue engineering through studying osteogenic differentiation level of human bone mesenchymal stem cells (BMSCs). Methods The BMP-2/PL compounds (B/P), formed by the BMP-2 and soybean phospholipid (PL), were dispersed in methylene dichloride, and then we mixed it with PCL and prepared the PCL-B/P composite scaffold and PCL-B traditional scaffold loaded with BMP-2 by phase separation method. The slow-release of BMP-2 from two kinds of scaffolds was observed with ELISA assay. The human BMSCs were cultured in the media containing PCL-B/P composite scaffold or PCL-B traditional scaffold, and the proliferation abilities and osteogenic differentiation levels of BMSCs on two kinds of scaffolds were detected and analyzed by CCK-8 assay and qPCR, respectively. Results Compared with the PCL-B traditional scaffold, PCL-B/P composite scaffold in this study showed a better slow-release effect of BMP-2 and a longer slow-release time of 22 days. The proliferation abilities of BMSCs on PCL-B/P composite scaffold were better than that on PCL-B traditional scaffold on the 7^th day, 14^th day and 21^st day of cell culture (P<0.05). The alkaline phosphatase content and mRNA expressions of collagen type Ⅰ, osteocalcin and osteopontin of BMSCs in the PCL-B/P composite scaffolds were significantly higher than those in the PCL-B traditional scaffold (P<0.05, P<0.01). Conclusion We have successfully prepared a PCL-B/P composite scaffold loaded with BMP-2. The PCL-B/P composite scaffold can slowly release BMP-2 for a long time and induce the proliferation and osteogenic differentiation of human BMSCs.