A simplified mathematic model was formed to estimate the soil infiltrability from the total water supply, the initial and saturated soil water content and the linear assumption of the soil water distribution based on the study of modified Green-Ampt model and the mass/water balance principle. The soil infiltrability estimated with this new simplified method is very close to the values calculated with the other methods. Comparisons were made between the predicted and measured soil water distribution. The average relative error was 4.18% which verified that the predicted one was very close to the measured values. The results showed that the newly suggested model could predict the soil water distribution along the horizontal soil column as a function of time very accurately. This new model is readily applicable to the related studies and applications. It has great importance for the study of hydrologic circulation studies.