Abstract: In view of the poor salt resistance of conventional drag reducing agent, a salt-tolerant drag reducing agent was synthesized by polymerization using acrylamide as raw material and introducing salt-tolerant monomer. Research has shown that the viscosity of the aqueous solution is 3.6~20.7 mPa·s at the addition of 0.05%~0.3%, and the drag reduction effect is the best at the addition of 0.15%, with the drag reduction rate of 72.6%,and the drag reduction effect is the best at the addition of 0.15%, with the drag reduction rate of 72.6%, which meets the requirements of reusing produced water to prepare fracturing fluid, and its salt tolerance and drag reduction performance are superior to conventional products. It has been applied in 4 wells on site in BM block of the southeast Sichuan. The reuse rate of produced water is 100%, and the field measured drag reduction rate is 73.2%~76.7%.Compared with the traditional powder drag reducing agent liquid preparation mode, it does not need to prepare the liquid in advance or mixing vehicles, which greatly reduces the labor intensity of liquid preparation, reduces the cost of liquid preparation by more than 70%, and improves the construction efficiency by 20%, which is of great significance to the fracturing operation.