Provided is an under-display camera assembly, including: an organic light-emitting diode display screen, a display region of which includes an under-display camera region and a non-under-display camera region, wherein a pixel density of the under-display camera region is set to be less than a pixel density of the non-under-display camera region; and a camera module, wherein the optical axis thereof is perpendicular to the surface of the organic light-emitting diode display screen, and the camera module is located at a rear end of the under-display camera region. Further provided is a corresponding terminal device.