By reviewing the methods and techniques of conventional prototype observation, this paper pointed out that difficulties and shortcomings exist in the prototype observation of high  speed flow characteristics. The basic principles and techniques of new coating trace method were proposed to solve these problems in the prototype observation, and the technical feasibility of this method was expounded based on laboratory experiment and preliminary application in engineering. Finally, the paper probed into the content and the technology way for further study, and looked into its application prospect.