Abstract: Microwave Radiation Imagers (MWRIs) onboard the FengYun (FY)-3A/B satellites of China Meteorological Administration were launched on May 28, 2008, and November 5, 2010, respectively. They both observe the Earth atmosphere and land surface at 10.65, 18.7, 23.8, 36.5, and 89.0 GHz with dual polarization. After extensive on-orbit calibrations, the MWRI Level-1 data were collocated in space and time with the data from Aqua Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E), F18 Special Sensor Microwave Imager Sounder (SSMIS), and Tropical Rainfall Measuring Mission Microwave Imager for cross-calibration. A forward radiative transfer model was used to simulate the clear sky brightness temperatures at the MWRI frequencies over ocean. The differences between MWRI observations and model simulations, referred to as “O-A, ” and the double difference results from pairs of MWRI and AMSR-E were examined. Comparing to the biases between AMSR-E/SSMIS measurements and model simulations, the biases for MWRI are small and stable. Atmospheric and surface geophysical parameters are retrieved from MWRI observations using the heritage algorithms. It is shown that these environmental data records from MWRI are comparable with those similar data products from AMSR-E and SSMIS. Their biases from each other seemed to be minimal.