This work aims to prepare diffusion coating on TC4 titanium alloy to improve its wear resistance. By using the method of pack cementation technique, TiB2-strengthened TiAl3 composite coating was prepared through firstly depositing B at 950~1100 ℃ for 4~8 h and then depositing Al at 950~1100 ℃ for 4 h. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersion spectrum (EDS) and wave dispersion spectrum (WDS) were used to analyze the morphology and structure of the coating. Based on the analysis results of microstructure, surface roughness, hardness and wear rate of the TiB2-strengthened TiAl3 composite coating, combined with the thermodynamic analysis of B and Al deposition processes, the formation mechanism and wear resistance of the TiB2-strengthened TiAl3 composite coating are clarified. The thickness of the TiB2-strengthened TiAl3 composite coating is about 37~108 μm and its surface roughness is about 5.485~9.320 μm. The composite coating is composed of boride and Ti-Al intermetallic compounds. The TiAl3 layer is the main body of the TiB2- strengthened TiAl3 composite coating, and boride phase is mainly distributed on the surface of the composite coating, forming TiB2 continuous layer or dispersing in the outermost part of the TiAl3 layer. The morphology and distribution of borides in the TiB2-strengthened TiAl3 composite coating can be controlled by adjusting the deposition temperature and time of aluminizing. When abrading with GCr15 under the condition of dry friction at room temperature, the wear rate of the TiB2-strengthened TiAl3 composite coating can be as low as 2.65×10–5 g/(N.m), which is reduced by 75.0% compared with the corresponding B deposition layer. The TiB2-strengthened TiAl3 composite coating shows better wear resistance than that of the B deposition layer.