The invention belongs to the field of smelting, and particularly relates to a titanium powder surface modification method. The titanium powder surface modification method comprises the following steps that firstly, titanium powder and an alkali metal (alkaline earth metal) chloride, metal titanium, sodium fluoride and titanium dichloride are mixed to be put in an alkali metal (alkaline earth metal) chloride molten salt with the temperature of 1099 DEG C to 1198 DEG C; then the titanium dichloride is dissolved by using strong solubility of the molten salt, titanium ions are taken as a medium, a metal titanium block is taken as a raw material, a disproportionation-comproportionation characteristic of a titanium element is used to promote deposition of titanium metal on the surface of titanium powder so as to modify the surface of the titanium powder and improve the spherical coefficient to improve the 3D printing performance and the sintering property of the titanium powder; after the reaction is finished, two-stage filtration is performed by using a porous plate and a sieve plate with the pore diameter of 0.21mm to 1.99mm, and then the residual metal titanium block and modified titanium powder are separated out correspondingly. According to the titanium powder surface modification method, the whole modification process is spontaneously performed, titanium atoms are transferred from the surface of the metal titanium block and are deposited on the surface of the titanium powder, and the key process can be controlled by means of parameters; the modification reaction of the titanium powder is performed in a molten salt bath, the ion diffusion condition of a reactant is good, the surface of the product titanium powder is smooth, and the spherical coefficient is high.