A calibration approach based on active vision for a light plane is proposed to achieve the self-calibration of a line structured light sensor. The proposed method is different from the previous plane fitting methods using the target points on the light plane, and the entire calibration process can be accomplished in two steps by several translational motions of a sensor. Firstly, the projections of parallel lines in the light plane are captured through some translational motions, and the normal vector of light plane is obtained via computing vanishing points. Then,in order to satisfy the model of perspective-three-points, the sensor is controlled to move along the set direction twice which is perpendicular to the normal vector, and the distance from the origin of camera coordinate system to the light plane is derived eventually. Experimental result shows that this calibration method has high accuracy, its average measuring accuracy is 0.015 4 mm, and relative error is about 0.183 0%. This calibration approach belongs to the self-calibration method without calibration targets, therefore, the calibration cost is reduced. It concludes that the whole process is easy, flexible and suitable for calibration on sites.