[Objective] The effects of canopy rainfall redistribution on surface runoff, erosion and leaching in poplar forests were discussed, in order to provide a theoretical basis for reducing soil erosion in agroforestry systems.[Methods] Taking the poplar-wheat intercropping system in Taihu Lake basin as the research object, the surface runoff, erosion and leaching were measured and analyzed, based on the field observation of rainfall, throughfall and stem flow of 101 rainfall events in 2013.[Results] ① The total rainfall was 943.5 mm.The throughfall, stem flow and interception were 796.2 mm, 7.3 mm and 140.0 mm, respectively, accounting for 84.4%,0.8% and 14.8% of the total precipitation. The small and medium-sized rainfall which was less than 10 mm occurred most frequently, accounting for 80.2% of the total rainfall events. ② Throughfall and stem flow were correlated with rainfall outside the forest (R²=0.993, R²=0.748 4). The stem flow started when the rainfall was greater than 5.5 mm. A negative function correlation existed between the rate of canopy interception and rainfall (R²=0.414 7). In addition to rainfall, the rate of canopy interception was also related to canopy leaf area index. ③ The higher the intercropping system stand density, the greater the canopy leaf area index, and the stronger the effects of canopy layer on surface runoff and erosion. ④ The average throughfall at 1.5 m from the trunk of a single poplar was reduced by 3.2% and 9.3% respectively compared with that at 0.5 m and 7.5 m, and the leached water decreased by 3.5% and 10.8% respectively. Besides, canopy structure played an important role in leaching loss.[Conclusion] ① The redistribution effect of poplar canopy on rainfall in intercropping system mainly depended on rainfall. The greater the rainfall is, the less significant the interception effect is. ② The increase of poplar intercropping can significantly reduce the surface runoff and erosion in the system. ③ The canopy of a single poplar tree at 1.5 m from the stem has the greatest effect on rainfall reduction and the least amount of leaching.