In order to calibrate parameters of the line structured light with hi gh efficiency,low cost and high precision,a calibration technique based on plana r target with only a pair of concentric circles is proposed in this paper.The me thod determines 3-D coordinates of points on the line structured light using the model of persp ective-three-point (P3P) and the principle of cross-ratio invariance.and then the equation of the plane of the l ine structured light is obtained from the points by least square method (LSM).Th e planar target is moved freely within the field of the camera′s view while kee ping the structured light projecting onto the outside region of concentric circl e on the target,and at least two images are acquired to complete the calibration .Finally,the calibration accuracy and overall scanning residuals are analyzed th rough some experiments.Experimental results indicate that this calibration techn ique has high accuracy,the RMS error of structured light calibration is approxim ately 0.05mm,the relative error of the measurement accuracy is about 0.3% and t he overall measurement accuracy is about 0.1mm.Furthermore,the method we propos ed is also suitable for other types of structured light with high generality.It concludes that the process is efficient,the calculation is simple,and the whole operation is easy,flexible and suitable for field calibration.