In order to comprehend signal similarities and differences observed by similar instruments on board different satellite platform, the infrared channel signals observed between FY-2C VISSR and TRMM VIRS during process of typhoon “Aili” from Aug. 27, 2005 to Sep. 3, 2005 are compared. Statistical results indicate that more than 70% samples have less than 5 K infrared temperature differences observed between FY-2C VISSR and TRMM VIRS. In the condition of clear sky, results display less than 1.5 K in average brightness temperature observed by VIRS than by VISSR, which is the same for the cloudy sky at the far infrared channel of the both instruments. However, there are relative large differences of brightness temperature detected by both instruments at the middle infrared channel in the cloudy sky, and these differences increase with the rising of cloud tops.