A Rotating fan-beam scatterometer (RFSCAT), which provides a set of different incidence and azimuth angle
combinations and wide continuous swath coverage, will be flown on the Chinese-French Oceanography Satellite
(CFOSAT). In this paper, a pre-processing algorithm is developed to estimate the backscatter coefficient (σ<sup>0</sup>) of
RFSCAT, which includes the procedures of system distortion correction, thermal noise removal, internal signal
calibration, and elimination of the observing geometry effects. The algorithm is then tested using the experimental data
from an airborne campaign. The estimated σ<sup>0</sup> are consistent with Nscat-2 geophysical model function (GMF), indicating
that the pre-processing chain acts well for RFSCAT.