A combined measurement method with PIV and schlieren technology is described in this article. The velocity field and the shock wave structure can be obtained simultaneously with this combined measurement method by a synchronous time controller and the post-processing. The color schlieren can capture the instantaneous image effectively and clearly, while the PIV can calculate the time average velocity field and put out with the visual image. Both of them are ripe technologies, they can setup easily and even get some commercial groupwares. In this article, this combined measurement method study the under expanded supersonic jet successfully. Not only limit in the under expanded supersonic jet, this combined measurement method also can apply in the other supersonic flow. They are complementary advantaged to the investigation of supersonic flow.