The calculation method of infrared transmission spectroscopy of boron-implanted HgCdTe epilayers was proposed based on multilayer model, transfer matrix and nonlinear least squares method. The results show that the transmission spectra of HgCdTe epilayers can be fitted very well by the theoretical calculation curves. By fitting, the carrier concentration, the mobility, the sheet carrier concentration, the refractive index and the extinction coefficient in B+ implanted zone are obtained. These parameters are consistent with those obtained from different Hall measurement before. The effect of B+ implantation on the transmission spectra of HgCdTe epilayers mainly comes from the changes of the refractive index and the extinction coefficient of HgCeTe material in B+ implanted zone.