With the visible-infra-red multispectral scanned images and the scanned day and night thermal images,the soil albedo image and the day-night thermal image can be done.With a few soil thermal inertia data measured in laboratory,the corresponding soil albedo and day-night temperature difference were measured synchronously in fields,through dualistic regression,a dualistic cubic formula was obtained.Using this equation and the soil albedo image and the soil temperature difference image,a soil thermal inertia image was obtained.Then the soil thermal inertia image was transformed into a soil moisture map,with the aid of regressing the soil thermal inertia to the coil moisture.The error of the soil moisture map ranged from -4.18% to 1.98%,the mean absolute value of the errors was 1.85%.