After the impoundment of Three degrading Gorges Reservoir, the ecological defence function of the riparian degrading zone will be weakened or lost. So, in the riparian zone and its above neighboring region, the construction of ecological protection zone can decrease the levels of the agricultural nonpoint source pollution and soil erosion, which is beneficial to the water safety and sustainable utilization of Three Gorges Reservoir. In the present study, according to the characteristics of water level fluctuation of Three Gorges Reservoir and the design concepts and management experience of riparian vegetation buffer region at home and abroad, the definition, function orientation and width estimation method of ecological protection zone of Three Gorges Reservoir have been discussed. Furthermore, the general idea has been provided for the ecological protection zone construction of Three Gorges Reservoir.