This work aims to investigate the difference of lapping process between different crystal surfaces of anisotropic gallium oxide wafer. High quality self-supporting diamond thick films were prepared by CVD method, which were characterized by SEM and Raman spectroscopy. They were used as tools to lap (100) and (010) crystal surfaces of β-Ga2O3 wafers in three different liquid environments to compare the tribological properties. The surface morphology, composition and wear mechanism of the tools were observed and analyzed by means of three-dimensional scanning system, SEM and EDS. The friction coefficients of (100) and (010) crystal surfaces are the highest in deionized water. When the liquid environment is glycol and triethanolamine solution, a very thin chemical reaction film is formed in the process, which reduces the furrow effect and the friction coefficient is small. The results show that the surface roughness of (100) and (010) crystal faces is the lowest when the liquid environment is triethanolamine. The surface roughness Ra of (010) crystal surface is smaller than that of (100) crystal surface after machining. There are some differences between (010) crystal surface and (100) crystal surface in different liquid environment, and (010) crystal surface is easier to obtain better surface quality than (100) crystal surface. In the process of machining, the wear mechanism is that two body wear occurs at first, and then three body wear occurs after a period of time.