Objective To solve the scaling problem of waterflooding pipeline of No.3 United Station in Jing‘an Oilfield. Methods Scale samples were analyzed by using scanning electron microscope and X-ray diffraction method. Ionic concentration of oil-water mixture in each station was analyzed by the analysis on oil and gas field water. A novel high-efficiency scale inhibitor Inhi-MPE was developed by orthogonal test L9(34) with self-made maleic anhydride- hydroxypropyl acrylate-sodium subphosphite (MASP), polyepoxysucc-inate (PESA) and ethylene diamine tetramethylene sodium phosphate EDTMPS) as raw materials. Scale inhibition performance of Inhi-MPE and commonly used PESA, AA/MA and PBTCA were evaluated according to evaluation method for behavior of inhibitor used in oil field. Results Scaling sample of the waterflooding pipeline was mainly made of calcium sulfate and a small amount of barium or strontium sulfate scale. The scale of waterflooding pipeline of No.3 United Station in Jing‘an was mainly mixed by two incompatible waters and produced the scale of CaSO4, CaCO3 and Ba(Sr)SO4 in the pipeline. The optimal level combination of the Inhi-MPE was MASP 10 g, PESA 7 g and EDTMPS 7 g. The scale inhibition performance of Inhi-MPE was improved with the increase of Inhi-MPE’dosage. The scale inhibition rate to the mixed water sample of No.3 United Station in Jing‘an was 93.71% when the dosage of Inhi-MPE was 100 mg/L. The scale inhibition effect of Inhi-MPE was best, AA/MA and PESA successively, and PBTCA worst under the same experimental conditions. These indicated that Inhi-MPE had excellent scale inhibition performance. Conclusion When Inhi-MPE is added continuously to the mixed water of the No.3 United Station in Jing‘an, the average quantity of water injection can be controlled at 608~628 m3 and the average pressure at 8.15~8.27 MPa, and both of them remain basically unchanged. It indicates that Inhi-MPE can retard effectively scaling rate of CaSO4, and ensure the stability of waterflooding quantity and the stableness of injection pressure. By this way, the scaling problem of water injection pipeline can be solved.