SSM/I data on the Bohai Sea of China from 1994 to 1996 have been studied.The sea ice algorithms of calibration/validation such as the brightness temperature index[AES/YORK TBI (Hollinger et al.,1992)] and ocean scattering index[OSI (Ferraro et al.,1996, The Bulletin of the American Meteorological Society, 77(5), 891-905)] are not applicable to the detection of regional sea ice of mid-latitude Bohai area.This paper presents a method of the scatfeting index SI and polarization index PI to identify regional Bohai Sea ice.Numerical results of vector radiative transfer for a model of a layer of sea ice over ocean simulate the relationship between SI/PI and sea ice depth, and others.It is employed to categorize the SI/PI indexes for the detection of sea ice.