Abstract: Through laboratory experiments, the variable process of soil infiltration rate and the distribution rule of soil moisture in wetting front were analyzed. Results show that the relationships between time and cumulative infiltration is a power function. The infiltration rate trend to zero is the sign to finish the infiltration. Through the concept of field and the experimental data of soil moisture, the simulation model of soil moisture in wetting front under non-pressure irrigation was established, and the model was tested with measured values. Results show that the experimental equation of soil moisture is simple, practical and has higher precision. The correlation coefficient between the measured value and the calculated value is above 0.899. The research result is important to guide the soil water adjustment and management.