Abstract: The key technological problems with these performance tests on EMP protection devices were analyzed. The process method of distortion-free transmission of pulse signals was presented. Based on microstrip designs, the special clamp for performance tests on EMP protection devices was developed. Via Vector Network Analyzer, the transmission characteristics of that clamp were evaluated. The test results indicate that microstrips can be used in the performance tests on EMP protection devices to reduce the influence of high-frequency reflection and radiation field created by strong EMP field and to improve the transmission quality of the pulse signals. It is by using the special clamp that the tests results can better reveal the characteristics of EMP protection devices.