Abstract: The dynamic hydraulic loads under the coupled effects of multiple physical fields in urban flood discharge channels under complex working conditions are difficult to accurately quantify, resulting in increased errors in peak flow calculation and affecting subsequent foundation reinforcement, embankment slope and retaining wall design content, leading to a decline in the quality of urban flood discharge channel structural optimization. Therefore, a research method for optimizing urban flood discharge channel structures under complex working conditions is proposed. Taking the renovation project of the flood discharge channel in Yuncheng City, Shanxi Province(Yongji section of Yaoxian Canal) as an example, the complex geological conditions within the project site are analyzed. Based on the complex geological conditions, a semi theoretical and semi empirical approximate formula for peak flow is used to determine the peak flow of different areas by combining the upstream inflow situation. The peak flow of each section of the flood discharge channel within the city is determined by cyclically summarizing the peak flow of different areas. The method of reinforcing the foundation with cement mixing piles is used to reinforce the weak soil in the active area of the flood discharge channel dam body. Starting from the optimization design of the stability of the embankment slope and retaining wall, the aim is to enhance the soil resistance ability while maximizing the safety and stability of the urban flood discharge channel structure. The optimization results show that the calculation error of peak flow rate for each section of the method is controlled within 15%, which can provide accurate data support for the design of flood discharge channel scale; The reinforced and optimized foundation has a bearing capacity higher than the required bearing capacity by more than 20 kPa, and the stability of the embankment slope and retaining wall meet the engineering requirements.