Abstract: The surface roughness of biomaterial is one of the important factors which affect the cell behavior. In order to regulate the surface roughness of silk protein biomaterials and evaluate the effects of the surface roughness of material on cell growth behavior, Antheraea pernyi silk sericin (AS) solution was used as the template to induce the nucleation of hydroxyapatite (HAp) crystals by wet chemical coprecipitation method firstly, and therefore regulated the surface roughness of AS films. Then, the surface morphology, roughness and elements of HAp/AS composite films were characterized with SEM, roughometer, FTIR and EDX. Finally, the cell morphology and proliferation rate of bone mesenchymal stem cells (BMSCs) on the surface of HAp/AS composite films were detected with SEM and CellTiter 96^® AQueous one solution cell proliferation assay reagent (MTS). The results show that the surface roughness of pure AS film is 0.15 μm. After mineralization for 1, 8 and 24 h, the surface roughness is 0.38, 0.46 and 1.20 μm, respectively. After mineralization of 24 h, some lobular compounds whose diameter is 30-80 nm can be observed on the surface of AS/HAp composite films. The resultant mineralized compound is HAp. HAp/AS films have good biocompatibility and the composite film whose surface roughness is 1.20 μm can promote the proliferation of BMSCs significantly. The roughness has important effect on attachment and morphology of BMSCs on the surfaces of HAp/AS films. Thus, the nucleation and growth of HAp crystal can be induced on the surfaces of biomacromolecules by the method of mineralization, there by regulate the surface roughness of materials, and investigate the cell behavior on the interface of materials.