The invention discloses a mounting, calibrating and checking system for a laser scanner. The system includes a pedestal, an imaging detection device, an auxiliary measurement device and an informationprocessing device. The imaging detection device includes a laser scanner, a video microscopic lens and an area array camera. The video microscopic lens can form an image on a target face of the areaarray camera after amplifying an object. The area array camera acquires scanning information and transmits the information to the information processing device. The auxiliary measurement device includes a parallel light source, a light beam modulator, an adjustable diaphragm, a focusing lens and a calibration board mounted on the pedestal. Light beams emitted by the parallel light source cast to the target face of the camera after passing through the light beam modulator, the adjustable diaphragm, the laser scanner and the focusing lens. Accurate measurement values used for mounting, calibrating or checking the laser scanner are obtained after software algorithm treatment on the acquired image information on the target face. The system has advantages of improving accuracy of scanning information of the scanner and ensuring performance indexes of the scanner.