SSM/I data ovor the desert areas of China is studied. Temporal variations of the brightness temperatures T

B

from SSM/I observations are presented. The polarization index of 37GHz channels is defined as an identification index to detect the desert distribution. Its spatial and temporal variations are discussed. The radiative transfer theory is used to simulate the T

B

of desert area at SSM/I channels

which includes the effect of atmospheric water vapor

surface roughness

and vegetation coverage

etc. This analysis has developed an useful approach to the desert study in China.