While UHF RFID tags being attached to the surface of various materials, there will be great errors when we adopt the traditional method of cable connection test to get the tags resonance characteristics. In this paper, we formed a model of tags powerreceiving, analyzed the relationship between the energy obtained by tag chip and frequency, and then proposed a contactless method to get the resonance characteristics of UHF RFID tags. This paper detailed the principle of using the relationship between frequency and distance to test the resonance characteristics, illustrated the design concept of testing software, built and completely implemented the contactless hardware test platform. Measurement results demonstrated that the proposed method and platform can test the tags resonance characteristics effectively. In practical applications, tags for different materials can be designed according to the resonance characteristics.