Abstract: A large amount of scum was generated which in turn created a vicious circle, resulting in the degradation of the water quality of the sewage station and the crude oil diplomatic water as well as the difficult operation of the system. Through in-depth analysis on physical properties of the sewage and scum, it was determined that the key factors were the formulation system and high alkalinity of the water. Thus, water conditioning was proposed as the core measures in addition to the research approach of source control and multi-scale measures centering the main process. The chemicals suiting the sewage treatment were screened out. Through the separate sewage recycling system of oil, gas and water, the water quality was stabilized, the mud yield rate at the centrifuge was improved, and the control of the scum generation was achieved. Finally, the water quality compliance rate was comprehensively maintained at 100% and the scum was controlled effectively.