Abstract: In order to meet the need for measuring the rectangular pulse radiation field with varying repetition frequency in the frequency domain, a measurement method using peak detection was investigated. A measurement approach was proposed to address the measurement instability and the measurement bandwidth limitation in measuring the rectangular pulse signal with varying repetition frequency using peak detection. The field strength correction factor was introduced and its mathematical model was established. After the solution and simplification for the field strength correction factor were completed, the research on the correction method was completed, which solved the limitation of the measurement instrument bandwidth. The requirements to the instrument settings were provided after the stability conditions for the field strength correction factor and the requirements from the measurement approach were analyzed to address the instability of measurement results. On the basis of the above, the measurement method using peak detection for the rectangular pulse radiation field with varying repetition frequency was developed. The experimental results showed that the deviations between the measurement results and the nominal values were less than 0.5 dB, indicating that the measurement method is effective and feasible. The measurement method can obtain the peak field strength and the average field strength of the rectangular pulse radiation field with varying repetition frequency by using a measurement resolution bandwidth smaller than the signal occupied bandwidth, which suits the needs for the measurement in open areas and provides a certain support for controlling electromagnetic environment. Also it is helpful for studying the measurement method for pulse radiation field with varying repetition frequency in other signal forms.