The midinfrared channel (3.5-4.0 μm) of Geostationary Meteorological Satellite FY-2C is special, at which earth outgoing longwave radiation and solar incoming shortwave radiation are basically of the same intensity. Therefore it is necessary to take into account both the atmospheric scattering and the thermal emission, and detailed researches are conducted on the two processes. Total radiation, thermal radiation and scattering radiation received from the midinfrared channel of FY-2C are simulated by using radiative transfer model SBDART. And the radiation characteristics and sensitivity to cloud droplet particle effective radius are analyzed. Then an empirical relationship was proposed about removing the thermal radiation emitted by the earth’s surface and clouds from the total radiation received in the midinfrared channel of FY-2C.