The invention discloses a surface modification method for a medical metal material. The surface modification method comprises the following steps: S1, polishing and cleaning the metal material; S2, generating an oxide thin film or a mixed oxide film on the surface of the metal material; and S3, further preparing a TiO2 film on the surface of the metal material by a sol-gel method to finish surfacemodification of the metal material. On the basis of guaranteeing the mechanical performance of the metal material and the biocompatibility of the TiO2 film, through the in-situ surface modification technology, the surface of the metal material is pre-treated, the interface bonding force between the TiO2 film and the metal material is improved, and the use stability and safety of the metal material are improved.