In order to realize multi-laser beam pointing to the micro-target, the micro-target needs to be located accurately in the experiment of high power laser facility. According to the need of the detecting apparatus, a measuring simulationsystem based on vision system is set up to implement the accurate location and pointing of target. This paper analyzes the effect about illumination light to the detection position of target based on the improved mean shift algorithm. A template matching method about correlation coefficient method is used to detect the center of target pinhole and the focus degree of image is employed to analyze the position accuracy of target hole when the image is out of focus. The experimental results demonstrate that the image detecting resolution is 0.4 μm and the position accuracy of measuring is 1.2 μm. When the defocusing amount is between -10 μm and 30 μm, the drift amount of center point is less than 1μm which can satisfy the measuring accuracy less than 8 μm.