Abstract: Vertical line source irrigation system can transport water to the root of fruit trees directly for increasing water use efficiency by reducing soil surface evaporation. A simulated experiment was performed to study the effects of line source length on wetted soil characteristics. Results showed that there were linear relationships between the square-root of infiltration time and the surface horizontal wetted radius, maximum horizontal wetted radius and vertical wetted depth of different line source length. The line source length had an unsignificant effect on the surface horizontal wetted radius and maximum horizontal wetted radius of soil. It also showed that there was a linear relationship between the square-root of infiltration time and the ratio of the surface horizontal wetted radius to maximum horizontal wetted radius of soil. The ratio of the surface horizontal wetted radius to the vertical wetted depth of soil increased trends with infiltration time but exhibited decreasing tendency with the line source length increasing. These results can provide references for determining vertical line source irrigation technology parameters.