Aiming at the problem of performance degradation caused by the irradiation of high energy particles in the space application of infrared detectors, the influence of displacement damage on the key parameters of HgCdTe infrared focal plane is studied by proton irradiation experiment. By comparing the performance changes of the infrared focal plane before and after irradiation, combined with the theory of semiconductor radiation effect, the influence mechanism of displacement damage on the infrared focal plane characteristics of HgCdTe was analyzed. The results show that the dark current, noise and number of blind elements increase after proton irradiation, and the magnitude of degradation is in proportion to the radiation fluence. The results will provide helpful reference to the research of radiation effects of HgCdTe infrared detectors.