Abstract: Using 5 μm average-sized diamond powder as the raw material, Ti powder and Al powder as binders, polycrystalline diamond (PCD) was prepared under high temperature (1350～1550 ℃) and high pressure (5.5 GPa) using a six-faced compression machine. The effect of sintering temperature on the phase composition, microstructure, and mechanical properties of PCD was studied. The results show that under high temperature and high pressure, Ti and Al react completely with diamond to form TiC and Al₄C₃ respectively, PCD is mainly composed of diamond, TiC and Al₄C₃. As the sintering temperature increases, the relative density, wear ratio, Vickers hardness and fracture toughness of PCD increases first and then decreases. When the sintering temperature is 1500 ℃, diamond is tightly wrapped by the binder without obvious pores between particles, therefore, PCD has the highest relative density, Vickers hardness, fracture toughness and wear ratio, which are 98.8%, 54.2 GPa, 5.23 MPa·m^1/2 and 6210, respectively.