Abstract: A study was carried out in a typical hilly region in Yunnan Province in order to investigate effects of organic farming measures for management of tea plantations on soil erosion. A water erosion prediction project(WEPP) model specific for mechanism of soil erosion on slopes was used to simulate effects of higher vegetation coverage and/or higher straw mulching rate on soil erosion on slopes. Results show that rainfall intensity is the major factor, rather than slope length, significantly affecting soil loss and sediment output in either conventional or organic tea plantation on slope. Straw mulching significantly increases soil nutrient contents in the surface soil layer, and at the same time reduces soil erosion rate remarkably, and the soil conservation effect is more obvious, especially in the cases of heavy rain shower and rainstorm. Soil erosion rate drops significantly when straw mulching rate reaches 1.0 kg·m^-2. The simulation shows that soil erosion rate reduces with increasing vegetation coverage. The simulation of combined effect of vegetation coverage and straw mulching indicates that the combination of different management measures can significantly reduce soil erosion and sediment yield, especially in tea plantations with low vegetation coverage, where the effect of straw mulching is more obvious.