It is an anionic water-soluble cellulose ether polymer obtained by chemical modification of natural cellulose. It is a high-performance thickener, filtration reducer, wall-building agent and gelling agent in water-based drilling fluid systems. Based on CMC, it has optimized salt resistance, calcium and magnesium resistance and temperature resistance. Its core features are high thickening, strong wall building, excellent filtration reduction and salt resistance superior to CMC-HV. It is suitable for fresh water and low to medium saline drilling fluid systems and is an upgraded basic treatment agent to replace CMC-HV.