A cinema projection method and system are provided, to perform GDR transformation on an original DCP while keeping a luminance component value of pure black unchanged. A transformed DCP has a brighter display luminance than the original DCP, and a display luminance of pure black remains unchanged. By adjusting the PWM, the brightness of a screen display is reduced. To ensure that the transformed DCP has a consistent display luminance with the original DCP, a luminance adjustment consistency mapping model of a local cinema is used to transform a standard PWM level of each frame of the original DCP, to obtain a local PWM level of each frame of the local cinema.