Based on the monitored data at the Jiedi station during 2003-2015, this paper analyzed the characteristics of the soil moisture in Cangzhou Region, and studied the law of the soil moisture change. Using the observed data, this paper also calculated the soil depletion coefficient K, obtained the monthly average value of K, and made a plan of soil moisture forecast plan. The correlation between the rainfall, soil moisture content before raining and soil moisture increase after raining was established to obtain the formula for increase of the soil moisture, so as to make correct forecasting. By verifying the observed data in 2015, the forecast plans of soil moisture depletion and soil moisture increase were evaluated, of which the precision can meet the requirement of the soil moisture forecasting in Cangzhou Region.