The simulated test was conducted by means of three kinds of soil column of 20cm, 40cm and 60cm length. The results were as follows. The amounts of phosphorus leaching from organic vegetable soil were 26 times more than that from conventional vegetable soil in the different length column when 780mm rainfall was simulated. Irrigation not only reduced the soil available phosphorus content, but also changed the characteristics of phosphorus sorption and desorption of different soils. In addition, organic cultivation increased phosphorus content in the groundwater more obviously than conventional cultivation. It is suggested that the risk of soil phosphorus leaching to the groundwater body from organic cultivation could be greater than that from conventional cultivation and some managements should be adopted at the development of organic cultivation to prevent phosphorus leaching IOSS.