In order to obtain three-dimensional data of engine cylinder head blank, a passive line structured light canning measurement system is designed. Calibration of the direction cosine of the movement of camera optical center is given based on principle of virtual binocular stereo vision. Stereo vision system consists of a single camera moving along the one-dimensional rail, which gives Rotation matrix R and Translation vector T between local coordinate system and global coordinate system. And then the origin of local coordinate system is conversion to the global coordinate system so that the line of movement of camera along the rail is fitted and its direction cosine is calculated. Three-dimensional topography of a certain cylinder head is scanned and the cloud data on this topography is obtained, from which the data of Intake port center coordinates is extracted. Finally, the three-dimensional data is dealt with reverse engineering software and surface reconstruction works well.