Following the successful launch of the ifrst polar-orbiting morning-conifgured satellite, FY-3A, on May 27, 2008, in a new Fengyun three (FY-3) series, the second afternoon-conifgured polar-orbiting satellite (FY-3B) was launched on November 5, 2010. The four-channel Microwave Temperature Sounder (MWTS) was onboard both FY-3A/B satellites, with designed channel frequency similar to channels 3, 5, 7, and 9 of the Advanced Microwave Sounding Unit-A (AMSU-A). This study assesses the quality of the brightness temperature measurements from FY-3B MWTS by comparing them with numerical weather prediction (NWP) model simulations and NOAA-18 AMSU-A measurements with the same frequencies. A strong latitudinal dependent bias is found for both MWTS channel 3 and AMSU-A channel 7. At channel 4, the brightness temperatures are contaminated within a small latitudinal zone (~30°-40°N) of the Northern Hemisphere. It is also found that the MWTS channel 4 bias is strongly asymmetric across the scan and the fourth ifeld of view (FOV4) of channel 4 is globally and systematically warmer than its neighboring FOVs. These anomalous biases may arise from sidelobe effect and interferences of the signal transmitted from some unknown sources. A quality control algorithm is developed to remove the anomalous data at MWTS channel 4 for its applications in NWP.%继新一代气象极轨卫星上午窗口星风云三号A星于2008年5月27日成功发射以后，下午窗口星风云三号B星在2010年11月5日成功发射。搭载于风云三号卫星上的微波温度探测仪（MWTS，MicroWave Temperature Sounder）有4个通道，分别与先进微波探测仪（AMSU-A，Advanced Microwave Sounding Unit-A）的3，5，7和9通道相对应。通过与模式模拟亮温以及NOAA-18 AMSU-A同频率观测亮温的对比，评估了风云三号B星MWTS观测资料的质量。研究发现，MWTS通道3和AMSU-A通道7的观测偏差有较强的纬度依赖性；MWTS通道4的观测资料在约30°-40°N的狭窄纬度带上受到了严重污染；并且，通道4的扫描偏差不对称，第4个像元的偏差全球系统性地高于其他临近像元。造成这些异常偏差的可能原因包括卫星天线旁瓣污染和未知来源的信号干扰。为了将MWTS观测应用于数值天气预报，提出了一个质量控制算法剔除通道4的异常观测资料。
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