The effects of heat treatment on the microstructure, mechanical properties and wear resistance of Ti6Al4V alloy melted by laser selective melting were systematically studied. The results show that the as-built sample has an acicular α" martensite structure. The increase of heat treatment temperature causes the decomposition of acicular α" martensite, which leads to the decrease of the hardness of Ti6Al4V alloy. When the heat treatment temperature is 800℃, the alloy forms an α"/α structure, which increases the tensile strength and elongation of the alloy by 12% and 23%, respectively. When the heat treatment reaches above 900℃, the mechanical properties of the alloy decrease sharply due to the disappearance of the α"/α structure, the coarse grains of the α phase and the increase of the content of the β phase. The tensile strength decreased from 935 ± 10 MPa to 815 ± 9 MPa, and the elongation decreased from 8.72 ± 0.2% to 3.09 ± 0.1%. With the increase of heat treatment temperature, the friction coefficient and wear rate increase linearly, which is completely opposite to the changing trend of hardness, and the wear mechanism is changed from single abrasive wear to abrasive wear and oxidative wear. This is attributed to the increase in the grain size of the alloy and the increase in the content of β phase, resulting in a decrease in the overall hardness of the alloy.