The second-generation geostationary orbit (GEO) quantitative remote sensing meteorological satellite had been developed by China. Channels of the satellite′s scanning radiometer are increased from four of 1st generation Fengyun-2 to fourteen, with eight infrared channels covering the infrared band from short band to very long band. The eight infrared bands are implemented by three assemblies, known as shortwave dual channel assembly (MS-IR), water vapor dual channel assembly (WV-IR) and long wave four-channel assembly (LW-IR). The MS-IR contains two 8 × 1 PV MCT detector chips, corresponding to two CMOS low-temperature amplifiers, to achieve the photoelectric voltage signal conversion and amplification. The WV-IR contains two 4×1 MCT detector chips. LW-IR contains two 4 ×1 and one 4×2 MCT detector chip. These assemblies have good electrical and optical properties, such as MS-IR D* is up to 1×1012 cm·Hz1/2·W-1. WV-IR D* is better than 8×1010 cm·Hz1/2·W-1. The response spectra of these eight bands are quantitatively controlled, and the response spectrum is limited to the inner and outer limits. The small spot scanning system test results show that there was no obvious optical crosstalk inside the assembly. The registration accuracies between the two bands were better than 0.01 mm. In this paper, these assemblies are described, as well as performance, such as electrical performance, chip registration, optical crosstalk and relative spectral response.