Abstract: In this article, nanosecond laser was used to pretreat carbon fiber reinforced plastics (CFRP) composite surface, realizing modifying its surface component, roughness and surface wettability. Then the bonding strengths were tested through tensile shear experiment. The surface morphology, contact angle, surface roughness and chemical component were observed and characterized via SEM, contact angle measuring instrument, optical profiler and XPS. The results indicate that with different laser parameters, the epoxy resin on the surface of CFRP composite can be removed, changing the surface component, roughness and surface wettability, and then improving the bonding strength. Compared with the untreated CFRP composites, after laser surface treatment, the bonding strength of CFRP composites increases with the increase of surface wettability and surface roughness, and also changing with the change of chemical component. On the basis of untreated CFRP composites, when the laser defocus is 5 mm, 10 mm and 15 mm, respectively, the bonding strengths are increased by 129.41%, 112.13% and 105.88%, respectively. The surface wettability and surface roughness of laser treated CFRP composites are greater than those of the mechanically-treated CFRP composites. However, the heat damage caused by nanosecond laser treatment has a negative effect on improvement of bonding strength. Therefore, the bonding strength of the nanosecond laser treated CFRP composites are lower than that of mechanically- treated CFRP composites. That is to say, laser treatment process should be furtherly optimized to demonstrate the advantages of laser treatment.