The invention relates to a method for coating a film on a surface of an X-ray reflector, and the method can be used for solving the problems of high interface roughness between films and mixing and diffusion between the films in the prior art. The method comprises the following steps: 1, washing a glass base; 2, heating and keeping the glass base warm, and carrying out backwash cleaning on the surface of the glass base; 3, coating a titanium film on the surface of the glass base; 4, carrying out backwash spurting on the surface of the titanium film; 5, coating a carbon film on the surface of the titanium film; 6, carrying out backwash spurting on the surface of the carbon film; and 7, cutting off the power supply, cooling down to room temperature and finishing the film preparation on the surface of the X-ray. The method is applicable to the field of thin film engineering.