This paper presents the experimental measurements of the complex dielectric constants in two groups of soil samples using the microwave network analyzer. One group is the laboratory prepared soil samples with different moisture and salinity contents. We evaluated real parts and imaginary parts of dielectric constants as a function of microwave frequency

salinity

and water content. The real part is strongly affected by the soil moisture

whereas the frequency and the salinity of soils have little influence on it. The imaginary part is strongly affected by salinity at low frequencies（f< 5GHz） .When f< 2GHz the imaginary part decreases with the increment of frequency; whereas

at higher frequencies it tends toward a constant. The longer wavelength band

such as L-band

has better sensitivity to soil salinity than shorter wavelength. Another group of soil samples were cllected in the Jilantai Salt Lake area. The measurements are well agreed with the group one. Then we analyze the simultaneous pass RADARSAT image at the Jilantai Salt Lake area. The correlation coefficient between the backscattering intensity values of the RADARSAT image and the real parts of the salt soil is 0.23

whereas the correlation coefficient for the imaginary part is 0.66. That indicates the backscattering coefficient of the radar image well correlated with the salinity of salt-affected soil.This study provides an experimental basis for future soil salinity monitoring using microwave remote sensing.