Parallel machine tool (PMT) has advantages of high rigidity, high precision, low inertia and simple mechanism. This paper focuses on static state errors that consists of component parts machining、work-piece orientation、mechanism combination for a 3-DOF parallel motion platform with intersecting rails. The positions of moving platform is measured by a laser displacement sensor to prove center departure of moving platform and to calibrate three heights of connect point. Inverse kinematics of this mechanism will be revised and precision of position of moving platform will be promoted in this study.