Recent progress of HgCdTe infrared detector with subwavelength photon trapping structure has been reviewed in this paper. A combination approach of finite element method and finite difference time domain method, which can be used for jointly simulating of "light" and "electricity" characteristics in infrared detector, was systematically introduced. Numerical simulation and analysis results based on the HgCdTe infrared detectors with subwavelength microstructure were also demonstrated. The theoretical analysis and experimental data have shown that the subwavelength microstructure can trap photons in active region of infrared detectors. The subwavelength photon trapping structure has a promising prospect on improving the performance of long wavelength infrared detector.