Abstract: In this paper, a new constraint on the homography of the plane at infinity is introduced and a new linear camera calibration technique is proposed based on it. Compared with the related techniques in the literature, the main advantages of our new technique are tow-fold. Firstly, it is less stringent to hardware, for example, it does not require the camera to undertake orthogonal motions which are usually difficult to be done without special hardware support. In contrast, our technique requires only one translation, and two general motions of camera, which can be easily done, for example, with a hand-held camera. Secondly, in the determination of the homography of the plane at infinity, it relies neither on projective reconstruction nor on the homography of a space plane, it needs only some image correspondences and epipoles, which are basic requirements for any camera self-calibration technique. In addition, we prove that for a given set of camera motions such as { (R,t1), (R,t2)},if (t1 ,t2) are not linearly dependent, then the homography of the plane at infinity under this motion set can be linearly and uniquely determined. Simulations and experiments with real images validate our new method.