Based on the experiment of one-dimensional vertical infiltration in laboratory,the effects of sodium polyacrylate (SA) on infiltration capacity into sand,loam,and clay soils and the fitting effect of different infiltration models are studied. Four concentrations of the SA (0 ,0.08 % ,0.2 % ,and 0.5%) were added to these three soils. Results showed that the initiation infiltration capacity of the three soils was the highest. The curve of cumulative infiltration volume went up quickly and then the upward trend went down with the process of infiltration. For the three types of soil without SA,the order of soils was loess soilsand soilLou soil,by the cumulative infiltration capacity. The concentration of SA was controlled in the range from 0.08 % to 0.5 % by weight. The infiltration capacity of these soils significantly decreased with the increasing of SA. The infiltration capacity of sand soil was affected most obviously by the concentration of SA. Based on the study,water infiltration into soil can be simulated well by Horton infiltration model and the fitting effect of Horton model is better than that of Kostiakov and Philip models.