Abstract: Distortion will occur when testing medical microwave products, due to its high power, high frequency, in the existing radiated emission testing process which will cause saturation non-linear of the pre-amplifier. It will lead to test distorted, the test results are not accurate. This article will improve the original test method by adding some suppressing-frequency devices to suppress the main frequency energy and avoid pre-amplifier saturation, eliminate distortion. All of this will ensure the test results are effective and relia ble.