BACKGROUND:At present bone marrow mesenchymal stem cel s act as the main seed cel s in bone tissue engineering, but only 0.001%-0.01%cel s are in the bone with difficulty in cel separation and purification. OBJECTIVE:To explore the biological characterization of human placenta derived mesenchymal stem cel s and biocompatibility with three-dimensional porous hydroxyapatite ceramic scaffold. METHODS:Human placenta derived mesenchymal stem cel s were morphological y observed and identified usingflow cytometry, fol owed by osteogenic, adipogenic, chondrogenic induction for 3 weeks. Afterwards, the potential of multi-directional differentiation was identified by alizarin red S, oil red O and toluidine blue staining. DAPI staining was used to observe the adhesion of cel s on the surface of the hydroxyapatite ceramic scaffold under scanning electron microscope. RESULTS AND CONCLUSION:The human placenta derived mesenchymal stem cel s showed long spindle shape and uniform size under the microscope;they highly expressed CD29 and D90, but did not express CD45 and CD106. Fol owing induction, mineralized nodules were observed by alizarin red S staining, lipid droplets by oil red O staining and blue-dyed toluidine blue staining. These cel s adhered wel to the scaffold surface, indicting they are suitable for bone tissue engineering.