The invention provides a back detecting, sorting and discharging device and method, and belongs to the technical field of discharging of intelligent detecting and machining equipment.The device comprises a back detecting module, a back detecting side hanging assembly, a detecting and carrying module, a translation side hanging assembly, a sorting translation steering assembly, a multi-column belt conveying unit, a bottom frame and a controller; the controller is in telecommunication connection with the back face detection module, the detection carrying module, the sorting translation steering assembly and the multiple rows of belt conveying units, and feeding, back face detection, quality judgment and screening, steering, transferring and discharging of materials are achieved through control. By means of the back detection, sorting and discharging device and method, back detection, quality judgment, sorting and precise discharging of the materials can be achieved, the discharging precision and efficiency are improved, and the device and method can be conveniently applied and popularized in the field of detection and discharging of plate-shaped materials such as 3C products, semiconductor wafers and photovoltaic silicon wafers.