The measurement method with correction for the pulse modulated radiation field using root mean square detection in frequency domain is put forward to solve the restriction caused by the resolution bandwidth. First,the measurement principle is proposed and the correction coefficients for field strength based on root mean square detection are defined. Then, the measurement result for the signal power and the correction coefficients for field strength are modeled theoretically and expressed by the power factor whose value can been worked out. Also the optimum selections of the resolution bandwidth and dwell time are discussed to simplify the correction method with the deviation precisely controlled. Finally, the experiment is carried out and it shows that the deviations between computation and measurement results of the correction coefficients are less than 1.00 dB. It proves that the measurement method is accurate and feasible. The peak field strength and average field strength can be accurately obtained by using any resolution bandwidth. So it is not limited by the performance of the instrument. The established method provides a certain support for ensuring the electromagnetic safety of equipment and also is helpful for researching measurement methods for pulse radiation field with other modulation modes.