Degradation of fracturing flowback fluid is significance for saving water resource and environment protection. In this paper，the oxidative degradation of the Changqing oil field sewage with high salinity and viscosity was carried out adopting the ultrasound-assisted Fenton oxidation method and the influence of different factors on the oxidative degradation reaction was investigated. Under appropriate reaction conditions that the molar ratio of H2O2 to FeSO4 was 3.7∶1，the ultrasound power was 120 W，the reaction temperature was 20℃，the reaction time was 18 min and the pH value was 6.17，the COD decreased from 10615.5 mg/L to 2351.3 mg/L ，the removal rate of COD reaching up to 77.85%；the chromaticity decreased from 2113. 8 CU to 20.95 CU， the turbidity decreased from 47.88 NTU to 0.12 NTU，the viscosity decreased from 1.79 mPa·s to 1.02 mPa·s，the salinity decreased from 7130 mg/L to 1045 mg/L. Ultrasonic assisted Fenton oxidation degradation of the flowback fluid could realize the decrease of viscosity and the removal of COD，greatly reduce the chromaticity and turbidity，which was advantageous for the following deep treatment.