A new method was used in the experiment that was focused on vertical leaching of phosphorus in paddy soils during the rice-growing season. Some steel cylinders were inserted into the soil to different depths to collect water samples in Yixing, Jiangsu province. Results showed that neither the concentrations of soluble P nor the total P in the leachate was high, being below 0.02mg/L or between 0.03~0.08mg/L, respectively. The vertical leaching rate was about 0.53cm/day. The total amount of P lost through leaching was 3.77kg/hm², 36% of which was from the depth of 0~20cm, when the P application rate was 30kg/hm² during the rice growing season.