A technique for metric reconstruction based on one triplet of corresponding vanishing line in three images is proposed in this paper. Firstly, the infinite homography is computed by using the vanishing line correspondence and the modulus constraint. Then the camera intrinsic parameters are determined linearly by using the property that the infinite homography preserves the image of the absolute conic. Finally a metric reconstruction is obtained. Experiments with simulated data as well as with real images show that the proposed method is workable and applicable in real applications.