In order to realize laser lighting for a small moving target in a region, a design solution of laser light system which consists of rotary mirror and point laser lighter was proposed. The relationship between laser light curtain and rotary mirror parameters which include sides, circumscribed circle diameter and rotate speed was deeply discussed. Using this laser light model, the average laser power density on the target is related to laser power, laser scanning speed, laser beam degree, camera exposure time and distance between target and laser light. The formula which reveals the internal relations above-mentioned was deduced. The results of simulation and experiment show that the above-mentioned solution of laser light system is feasible and the formula is correct. The laser light system can be used to light for vision measurement system and can meet the expected results.