A method of selecting and confirming materials with W and B4C for X-ray broadband multilayer film is presented. The minimum bilayers number of X-ray broadband multilayer film has been confirmed by using BERNING formula at the wavelength 0.154 nm. After introducing the suitable merit function, a broad angular broadband W/B4C multilayer film has been designed successfully by using genetic algorithm. The flat reflectance of broadband multilayer film is 40% in the wavelength 0.154 nm at the grazing incidence angel (θ) of 0.5°～0.9°. The multilayer film has been fabricated on the magnetron sputtering system. A flat relative reflectance spectrum curve has been measured at the grazing incidence angle (2θ) of 1.0°～1.8° by X-ray diffractometer.