When measuring the transient response of MWIR HgCdTe photovoltaic devices, the device presented a special bimodal pulse response phenomenon when the surface position of the device irradiated by the laser spot was far away from the photosensitive surface. It is analyzed that the abnormal double pulse phenomenon was due to the time difference between the drift of minority carriers in the photosensitive region and the diffusion of minority carriers collected laterally outside the photosensitive region. By applying reverse bias to the device, the impulse response changed from bimodal to unimodal with the increase of reverse bias, which verified that the lateral collection of minority carriers was the main reason for the bimodal formation of the device. The minority carrier lifetime of p-region materials was obtained by fitting the second peak. Comparing the minority carrier lifetime obtained from the transient response with that obtained by the theoretical calculation and the photoconductivity decay method of the p-type MWIR HgCdTe material, it is found that the trends of the minority carrier lifetime obtained from the three methods with temperature are basically the same, which indicates that the minority carrier lifetime of MWIR HgCdTe material can be obtained from the transient photoresponse.