Abstract: Rotary coupon corrosion test, static scale inhibition test, dynamic simulation test and potentiodynamic polarization curve test were used to evaluate the performance of anticorrosion and scale inhibition of low phosphorus corrosion inhibitor RP-12 (AQ) in circulating water in which wastewater was reused. Its anticorrosion mechanism was studied. Industrial tests were carried out in circulating water systems in Sinopec Anqing petrochemical company. The research results indicate that when the cycle of concentration stays at 4.8~5.2, RP-12 (AQ) has a good corrosion inhibition and scale inhibition effect in the range of ρ_RP-12(AQ)=90~110 mg/L. It is a kind of mixed corrosion inhibitor which mainly inhibits the anodic reaction. The results of industrial application reveal that the average corrosion rate of two circulating water systems is 0.002 mm/a, and the adhesion rates being 3.62 mg/(cm²·mon) and 5.43 mg/(cm²·mon) respectively, which meet the demands of water treatment. The technical route of reusing properly treated wastewater in circulating systems, as well as the implementation of low phosphorus corrosion and scale inhibitor has remarkable social benefits.