Inspired by the technique proposed by Zhang in [13], we proposed a new camera calibration technique, which only requires observing three or more planar concentric conics at a few (at least two) different orientations. All computations involved are linear matrix manipulations. Compared with the classical techniques where an expensive calibration pattern is commonly used, our technique is easy to implement and more flexible. Using Conics also simplifies the problem of correspondence. Both computer simulation and real data are used to test the proposed technique.