1.Introduction
On June 10th 1997 China launched (FY-2) Geostationary Meteorological Satellite into earth-synchronous orbit with a Long March-3 rocket at Xichang Satellite Launch Center. The satellite is positioned at E105o,35800 Km above the equator. Onboard the satellite thee is a multi-channel scanning radiometer (MCSR) which can acquire simultaneously earth images from visible, IR and water vapor cannels. The MCSR I the main effective payload onboard the satellite with the following functions:

1. Taking visible cloud images at daytime, IR images and water vapor profile day and night above the earth and providing realtime meteorological information.
2. Obtaining upper and lower wind information from the movement of tracing cloud, forecasting timely typhoon, cold-air outbreak, whirlwind and other disastrous weather.
3. Providing temperature at ocean surface, analyzed cloud image and temperature profile of cloud top after data processing.

The MCSR was developed by the Shanghai Institute of Technical Physics, Chinese Academy of Sciences. This paper mainly introduces the performances, operation principle, basic structure and in-orbit operation of the instrument.