The invention discloses a device for fast detecting the two-dimensional morphology of a wafer substrate in real time and belongs to the technical field of nondestructive testing of a semiconductor material. The device comprises N PSDs, N laser beams, and a first light-splitting element, wherein the N laser beams are arranged along a straight line, the N is a natural number more than 3, and the N PSDs correspond to the N laser beams one to one. The N laser beams are emitted to the first light-splitting element so as to form incident light after passing the first light-splitting element. The incident light is emitted to a wafer substrate and forms N incident points on the wafer substrate along the radial direction. The incident light forms N first reflected light beams after being reflected by the wafer substrate. The first reflected light beams are subjected to the transmission of the first light-splitting element and then are emitted to the PSDs corresponding to the N laser beams in order to form N light spots. The device is adaptive to a sapphire substrate on a high-speed rotating graphite disc.