This paper introduces a new method of optical non-contact measurement, by using four beams of laser and position sensitive detector to measure position and angles, so as to determine position's posture of the motional object at some instant. The analysis and research on the internal composition of the system and its signal processing are made. The experiment proves that the system has many advantages: high accuracy, good restability, fast response, wide measurement range, composition compactness and low cost. So, this measuring system has a good future to apply in industry because of its attractive performance/ cost ratios.