Abstract: Periodic micro-grooves with different widths (20, 40 μm and 60 μm) on the surface of polyetheretherketone (PEEK)/mesoporous calcium magnesium silicate (m-CMS) composite were prepared by femtosecond laser. The effects of the width of micro-grooves on the adhesion, proliferation and differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) were investigated. Results showed that the micro-nanostructures were formed in the inner surface of the micro-grooves after ablating using femtosecond laser, which exhibited a large number of mesoporous calcium magnesium silicate particles. In addition, the roughness (R_a = 5.15 μm) of the inner surface of the micro-grooves was significantly improved as compared with the grooved ridge (R_a = 1.53 μm) that was absent of treatment by femtosecond laser. Moreover, with the increase of the width of the micro-grooves, the protein adsorption of the composite surface was obviously enhanced, which significantly promoted the adhesion of rBMSCs on the composite surface. Furthermore, when the width of the micro-grooves was 20 μm, the cells did not display specific growth orientation on the composite surface. When the width of the micro-groove was 40 μm, a small number of cells grew along the groove orientation. When the width of the groove was 60 μm, a large number of cells grew along the groove orientation, and the cell body was plump with filamentous pseudopodia extending, which indicated that the composite surface not only significantly promoted the adhesion, spreading, proliferation and osteogenic differentiation of cells, but also induced the growth of cells along the groove orientation. In short, periodic micro-grooves on the composite surface were prepared by femtosecond laser, and the width of micro-grooves on the composite surface could regulate and control the behaviors of cells, in which appropriate width (e.g. 60 μm) of micro-grooves was conducive to stimulate cell responses.