Abstract: The laws of soil water movement of point source interference infiltration and evaporation using super absorbent polymer were analyzed according to the laboratory experiments. Time-domain reflectometer(TDR) was buried in the bin with homogeneous soil to measure soil moisture automatically, and the software suffer was adopted to draw the water isobar. Results show that under the influence of super absorbent polymer, the soil moisture of the layer with super absorbent polymer reaches 23.60% rapidly during the infiltration, which is lager than that of 0～20 cm and 30～60 cm soil layers. The moistures of all layers decrease during the evaporation. In the 110th day, the soil moistures in 0～20 cm and 30～60 cm layers are 3.5％ and 4.5％, respectively, while the soil moisture in 20～30 cm is only 12.5%. Therefore, the application of super absorbent polymer can keep soil moisture for the root layer of crop.