This paper presents the expressions for imaginary part of dielectric constant of moisture salt soil at low and high frequencies respectively

which is functions of（1） soil water content and（2） soil salt content.This paper carried out a series of relevant studies

including: the relation of imaginary part of dielectric constant ε″ and soil bulk conductivity σ

a

;relation of soil bulk conductivity σ

a

and conductivity of soil solution σ

w

;relation of conductivity of soil solution σ

w

and soil solution concentration S

M

v

;and relation of soil solution concentration S

M

<

sub

>

v

and soil salt content S have been established gradually(ε″～σ

a

～σ

w

～S

M

v

～S).Based on these relations

the relation of ε″ and S

M

v

had been established

which is the dielectric imaginary part model for wet and salty soil.Dielectric constants of 150 samples from five soil types had been measured with microwave net analyzer at the 396 frequencies ranging from 0.2GHz to 20GHz with the interval of 0.05GHz.These measured data were applied to calibrate the dielectric imaginary part model and then achieved the calibrated model at different frequencies.In addition

other 41 soil samples from Jilantai had been measured to test the dielectric model;as a result

the calculated value from model and the measured value had a strong correlation.Finally

the paper made the conclusions:（1） effect of salt content will decrease with the increasing frequency;（2） soil type has little influence on imaginary part of dielectric constant.