Abstract: The side production operation of Xiwan open pit Coal Mine is greatly affected by burnt rock water. In order to reduce the influence of side water gushing on stripping operation and reduce the damage of mine drainage to the ecological environment, the scheme of using clay-cement slurry to construct clay-based flexible curtain water partition wall is proposed to block the passage of burnt rock water and surface water into the pit and realize water-preserving coal mining. The clay stripped from the pit is used as the raw material, and the clay-cement grout ratio obtained through the field test is used as the grouting material for the construction of curtain waterproof wall. After the construction of the curtain wall is completed, the displacement of the mine decreases by 89.82%, the water level inside and outside the curtain wall changes obviously, and the vegetation around the pit can be better restored. compared with the cement-fly ash slurry scheme, the cost of grouting materials is saved by nearly 0.88 million yuan. Engineering practice shows that the clay-based curtain wall has good water resistance, outstanding economic benefit and obvious ecological benefit, and the water conservation mining has been realized. It provides a new method for water gushing treatment and water conservation mining in the side of open pit.