In order to solve the problem that there is not test specification for the railway applied power converter noise survey, a method of noise survey for power converter based on the envelope method was proposed. The method was suitable for most of the laboratory and could make the difference between the results from laboratory measurement reproducibility standard deviation less than or equal to 3.0dB(A), which could ensure the scientific and accuracy of test data, at the same time, it was beneficial to compare the capability of noise survey between different laboratories. It also provides a practical specification for noise survey of power converter.