This paper describes how to carry out environmental impact assessment in an envi-ronmentally sensitive zone. The principles, the train of thought and methods are proposed in this paper. We have made the water environmental impact assessment on the engineering pro-ject of technical reform in Guiyang Battery Mill. The basis for engineering construction and environmental protection in this mill has been laid dawn. This paper describes how to carry out environmental impact assessment in an envi-ronmentally sensitive zone. The principles, the train of thought and methods are proposed in this paper. We have made the water environmental impact assessment on the engineering pro-ject of technical reform in Guiyang Battery Mill. The basis for engineering construction and environmental protection in this mill has been laid dawn.