In this paper, we present a new stereo approach for tracking human face by using only two cameras in system. One pan-tilt camera is used for tracking person focused on face. One static camera cooperate with pan-tilt camera are used as a stereo system to estimate face 3D position. We propose to update relative position between cameras to reflect camera moving and the change of relative position. Experimental results shows that our proposed system is able to track one person in camera viewing and can estimate the 3D moving path of interesting person.