To enhance the calibration accuracy of the line structured light sensor (LSLS), we propose a novel calibration method based on the planar reference target. A method is brought out to calculate the coordinates of the reference target point centers and the laser plane equation in the camera coordinate system. These reference target center points are projected onto the laser plane. The world coordinate system is established with the projection point of the lower left corner as the origin. The corresponding world coordinates for each center of the target point, which has known pixel coordinates, can be obtained. The mapping relationship between the arbitrary pixel coordinates and the world coordinates is achieved via the polynomial fitting and the calibration of sensor is finished. The calibration results are the coefficients of the polynomials, which are convenient for storage and use. The calibration accuracy is analyzed. The results show that the root mean square of distance error between each testing points and the first point is 0.0216 mm, which is 22% lower than the classical method. The proposed method has certain advantages in high-precision calibration of LSLS.