Ti-3Cu alloy exhibits excellent mechanical properties, corrosion resistance and antibacterial properties. Alkali heat treatment is an effective surface treatment method for titanium alloys, which can improve the surface biocompatibility of titanium alloys. The effect of alkali heat treatment on the microstructure, surface roughness, contact angle and antibacterial properties of Ti-3Cu alloy were studied in this research to reveal the possibility of applying alkali heat treatment to biological surface modification of Ti-3Cu alloy. The results have shown that a layer of titanate gel was formed on the surface of titanium alloy after alkali heat treatment, and a large number of nano-sized pores with a size of about 100 nm were distributed homogeneously on the surface of the gel layer, which reduced the roughness of Ti-3Cu alloy but improved the hydrophobicity of the alloy surface. The formation of the titanate gel layer on the alloy surface reduced the antibacterial property of the alloy from 92% before treatment to 77% after alkali heat treatment. The bacterial adhesion test also confirmed that alkali heat treatment reduced the antibacterial property of the alloy. It is believed that the titanate gel layer partly blocked the contact between Ti₂Cu phase and bacteria in the alloy, so the antibacterial effect of the alloy decreased.