To measure the 3D characteristics of a certain diesel engine cylinder head, the whole point cloud of the cylinder head is obtained through a system consisted of CCD, linestructured light and a closedloop feedback control trigger device. The normal vector of surface is calculated. The upper plane of the cylinder head is fitted using random sample consensus in the article. Then the coordinate system is converted, which establishes the foundations for the following position reference. Points on the internal surface of cylinders are extracted using SAMODEL_CYLINDER in PCL. The inner axis vector, coordinate of a certain point on the axis and radius can be obtained through PCL. The measurement results are compared with the standard size, the fitted results using PCL have much accuracy.