The determination of slope protection scheme is an important link in highway design stage. The objectivity and scientificity of decision-making results directly affect the safety of highway life cycle. At present, the decision-making of ecological slope scheme of expressway in flood detention area is mainly based on the directional empirical judgment, and lacks the quantitative theoretical evaluation. Therefore, based on the binary quantitative comparison method, entropy weight method and grey target decision-making theory, a decision-making model for the ecological slope evaluation of expressway in flood detention area is established. In this model, multiple factors of the decision making for the ecological slope scheme are comprehensively considered from three aspects of economy, technology and society, and 11 evaluation indexes are selected to build the index system. The entropy weight method is used to calculate the index weight to reduce the influence of human subjective factors. Combined with the grey target theory, the target center distance of each evaluation scheme is calculated to make the best scheme. Finally, taking the ecological slope scheme decision-making of Jinshi Expressway as an example, the above method is applied and verified. The practical results show that this evaluation model can accurately evaluate the advantages and disadvantages of ecological slope scheme of expressway in flood detention area, and has a certain rationality and feasibility.