In order to resolve the CaCO₃、CaSO₄ scaling problem of Huaziping Block of Changqing oilfield，The scale inhibitors of 1.0G PAMAM-COONa and 2.0G PAMAM-COONa were obtained by the reaction between polyamidoamine （PAMAM） and chloroacetic acid，and then the molecular structures was established by FT-IR and elemental analysis. The scale inhibition performance of 1.0G PAMAM-COONa and 2.0G PAMAM-COONa tor CaCO₃、CaSO₄ was studied，and the scale inhibition performance of the complex scale inhibitor PNF-2.0G ，composed of the scale inhibitor PNF and 2.0G PAMAM-COONa at mass ratio of 1∶1，to the blend water of produced water Block Huaziping and the injection water at mass ratio of 1∶1 was studied. In addition，the field test was conducted. The results showed that the scale inhibition of PAMAM-COONa to CaCO₃ and CaSO₄ was better than that of PAMAM，and the scale inhibition of 2.0G PAMAM-COONa to CaCO3 and CaSO4 was better than that of 1.0G PAMAM-COONa at the temperature of 60℃ . At the dosage of 20 mg/L，the scale inhibition rate of 2.0G PAMAM-COONa to CaCO₃、CaSO₄ was about 95.64%，92.35% ，respectively，while the scale inhibition rate of 1.0G PAMAM-COONa to CaCO₃、 CaSO₄ was about 82.25%，89.36%，respectively. As for the blend water of the produced water of 97-42 well and the injection water， when the addition of was 20 mg/L，and the scale inhibition scale of the 2.0G PAMAM-COONa and PNF was 75.53% and 60.5%， respectively，while that of the PNF-2.0G was 95.56%. As for the blend water of the produced water of 100-45 well and the injection water，the scale inhibition rate of 2.0G PAMAM-COONa and PNF was 38.5% and49.5%，respectively，while that of the PNF-2.0G was 98.91%. The field test results showed that the compound scale inhibitor PNF-2.0G played an excellent scale inhibition effect.