In order to obtain the ideal grain size in PVD process, a precise control of nano-grain size of micro-control method, and precise control of grain size of the micro-control method was introduced. Using MATLAB’s powerful ability to circulation calculated, and using vector overlay character of light, the interference of light was simulated. the young’s interference, the three-source interference and the multi-sources interference were researched and analyzed. By analysis the rule of stripes of interference is got. If the light sources are in a linear arrangement, the stripes will be chaotic. And if the light sources are arranged in regular polygon, the stripes in middle of sources are regular. And the strengths distance of three sources is λ√3, four is λ√2, six is 2λ. If the size of regular area is 1 cm2, the distance of source is 0.1m (threesources) and 1 m (foursources).