The control of combined sewer overflow(CSO)is a key part of improving the quality of urban water environment, and the related indicators and the formulation of standards are still weak. Technology-based emission control indicators mainly include overflow frequency, overflow volume capture rate, pollutant emission concentration limit, CSO efficiency and dilution, etc. Due to the lack of comprehensive evaluation of these indicators on CSO water quality and quantity control effect, the index of CSO pollution load proportion in rainy season is proposed. The control indexes based on the water quality assurance of receiving water include acute ammonia poisoning, dissolved oxygen concentration and bacterial standard, etc. This paper summarizes the basis for determining the CSO control standard, which is mainly divided into three parts: determining the CSO pollutant discharge standard by analogy with separate sewer system pollution load, establishing the CSO effect standard according to engineering practice effect, formulating different control levels of CSO according to the use of water body. On this basis, under the guidance of the concept of “finding out the background, making clear the goal, and systematic treatment”, the CSO control standard system and treatment technology route with the goal of meeting the water quality standard of receiving water body are proposed to provide reference for the formulation of CSO standards in China.