The reasons and characters of soil and water loss that caused by 500 kV overhead power transmission lines(OPTL) construction were analyzed.On the basis of the analysis and combined the project example,a practical soil and water conservation system were presented according to the ecological environment in earth-rocky mountainous area of southwest.And in accordance with the problems that existed in soil and water conservation scheme process of 500 kV OPTL,some related advices were proposed.The research results will be helpful for supplement the soil and water conservation system in 500 kV OPTL in earth-rocky mountainous area of Southwestern China,and meanwhile,provided a reference for the similar project construction in the area.