The microstructure of PMMA was prepared by femtosecond laser processing system.The wettability mechanism of PMMA surface was studied by adjusting the number of laser processing and the size parameters of microstructure.Firstly,the grating structure and square column structure were fabricated by laser.The surface morphology and wettability of the microstructure were measured and analyzed by the super depth 3D microscope and contact angle measuring instrument.The influence of different laser processing times and microstructure size on the wettability of the surface was studied.The results show that the contact angle of the surface microstructure of PMMA decreases with the increase of the grating spacing,and increases with the increase of the grating height,and the maximum contact angle reach 120 °.Compared with the grating structure,the contact angle of the square column structure is larger,which is close to the theoretical value.The wettability of PMMA can be changed from hydrophilic state to hydrophobic state by laser processing of the surface microstructure of PMMA.Too small spacing of the microstructure will lead to the accumulation of splashed melt in the structure channel during laser processing.