Abstract:Simulation of dynamic soil moisture in farmland is the important basis of agricultural water management. Based on the water balance equation of root zone, and taking the lower boundary water flux of root zone into account, a farmland soil moisture simulation model was set up, in cluding crop evapotranspiration model, lower boundary water flux model and water balance equation. The parameters of the model were fixed by the observation data of soil moisture through the winter wheat growing season in the irrigation experimental base of Shanxi Technical College of Water Conservancy in 2007 and 2008. The soil moisture simulated by the model agreed well with the measured ones, the multiple correlation coefficient reached 0.9555; and the F test reached extremely significance level. The established farmland soil moisture simulation model can be used to calculate crop evapotranspiration, lower boundary water flux in root zone and field soil moisture; and the mean calculation precision can reach 3%-11%.The result shows that the model deals well with the field soil water transform process.