Abstract： Objective To construct the tissue engineering bone by bone marrow mesenchymal stem cells (BMSCs) cultured on poly-lactide-co-glycolic acid (PLGA) modified with type Ⅰcollagen and recombinant human bone morphagenetic protein 2 (rhBMP-2). Methods BMSCs were isolated and cultured in vitro. The cellular configuration was observed continually under inverted phase-contrast microscope, and the cell exterior antigen was analyzed by flow cytometry method. PLGA was made by phase separation and modified with type Ⅰ collagen and rhBMP-2. The biomaterial structure was examined by scan electron microscope. The third generation BMSCs were cultured on PLGA. The adhesion of cell to biomaterial was examined by scan electron microscope as well. The complex of BMSCs-PLGA was then cultured for 6 h in SD rat muscle and was observed two months later by HE staining. Results BMSCs could be isolated and cultured in vitro, and the cell morphology was spindle. They expressed CD29, CD44, but did not express CD34,CD45. The average pore diameter of PLGA modified with type Ⅰ collagen and rhBMP-2 was 100 μm, the interval porosity was 90%, and PLGA had good adhesion with BMSCs. Positive staining and strong reaction for HE staining of the bone tissue in the complex was observed. Conclusions BMSCs can be cultured stably in vitro for long time, and are good seminal cell of tissue engineering. The PLGA modified with type Ⅰ collagen and rhBMP-2 has good adhesion with BMSCs. BMSCs cultured on PLGA modified with typeⅠ collagen and rhBMP-2 can construct the tissue engineering bone in animal body.