Based on (211) B CdZnTe substrate, PPP type medium-wave and long-wave dual-band HgCdTe material was prepared by molecular beam epitaxy. The medium-wave and long-wave dual-band 640×512 infrared focal plane detector assembly was fabricated by mesa-hole etching, sidewall passivation and other processes. The test results of MW/LW dual-band HgCdTe material show that the macro defects (2~10 μm) density is about 773 cm^-2. Then, the materials were tested by XRD double crystal diffraction half peak width (FWHM) and etch pit density (EPD). The FWHM measured by XRD is about 31.9 arcsec, and the EPD is about 5 ×10⁵ cm^-2. The etching depth of dual-band device chip mesa reaches 8 μm or more, the depth-width ratio is more than 1∶1, and the sidewall coverage is 72.5%. The test results of dual-band IRFPAs show that the response range is 3.6~5.0 μm and 7.4~9.7 μm. The crosstalk of medium wave to long wave is 0.9%, and long wave to medium wave is 3.1%. The average peak detection rate of medium wave and long wave reaches 3.31 × 10¹¹ cm ? Hz^1/2/w and 6.52 × 10¹⁰ cm ? Hz^1/2/w, while the NETD and effective pixel rate are 17.7 mK, 32.8 mK and 99.46%, 98.19%, respectively.