In view of the poor anti-noise performance of traditional methods, the principle of camera calibration is analyzed based on calibration template with planar circles, and a new calibration technique is proposed based on pin-hole perspective model. Firstly, the edges of image ellipses are located in sub-pixel by spatial-moment operator. Then elliptic equations are obtained by the Least Square Fitting method, and common tangents of two arbitrary ellipses are also calculated. Finally, the extrinsic and intrinsic parameters are computed by the Radial Alignment Constraint (RAC) model. Experiments results indicate that proposed method has a goof performance of lower computation complexity and higher precision.