A projection display system includes a control assembly, an optical path changing device, a light source assembly, a digital micromirror device, and a projection lens. The control assembly is configured to determine whether a resolution of an image to be projected is greater than a preset resolution. If the resolution of the image to be projected is greater than the preset resolution, the control assembly divides the image to be projected into N sub-images, wherein N is greater than or equal to 2. For each sub-image: the control assembly is further configured to determine a first signal, a second signal, and a third signal according to the sub-image, send the first signal to the light source assembly, send the second signal to the digital micromirror device, and send the third signal to the optical path changing device. The projection lens is configured to project the N sub-images at different times.