Microwave humidity sounder (MWHS) is one of payloads on the Fengyun-3A (FY-3A) satellite. This paper introduces its structure, operation status and data receiving and processing. The paper constructs an inversion model using artificial neural network (ANN) algorithm, and makes comparison with advanced microwave sounding unit advanced microwave sounding unit-B(AMSU-B). The results demonstrate that the model can be operated successfully. Using the simulated brightness temperatures from MWHS from July to December in 2008 in Beijing, the paper derives water vapor density profiles and gives analysis of root mean square. Meanwhile, the paper focuses on brightness temperature values of different scanning lines when the typhoon comes. The paper demonstrates that FY-3A satellite MWHS can retrieve the water vapor density profiles, cloud liquid water and other related information. Also, in the process of monitoring the tropical typhoon and cyclone and judging the trend of them, FY-3A satellite MWHS also plays a very important role.