In order to solve the calibration problems in line structured light sensor systems such as requirements for high accuracy calibration models, complicate calibration procedures and so on, a calibration method based on perspective-three-points was proposed. A calibration model was established by introducing a planar target that could move freely with three collinear and known mutual location points. The calibration point coordinates in a camera coordinate system could be calculated by using the imaging information of three points and the light stripes on image plane of the camera. The spatial pose between the camera and the light plane could be calibrated by moving the reference plane at several arbitrary places in the sensor range. Experiments show that relative accuracy of the sensor is about 0.72%.The method is suitable for the field calibration,for it has advantages in its simple and flexible calibration, the cost of calibration equipment, and not to calculate the transformation matrix among different coordinate systems.