Abstract: A simple field calibration technique was described to calibrate binocular vision senor for 3D measurement. The technique only required two cameras to observe a planar pattern shown at one position, and it did not need assistant structures. There were many control points printed on the planar pattern, through these control points to compute the homography between the model and its images. By combining evolutionary optimization strategies to get the principal points of two cameras, the focal lengths and the external parameters can be computed from homography. Compared with classical techniques, the proposed technique is simple and easy to use, and is applicable to field calibration.