AbstractIn this study, the plane interchange adopts the form and traffic organization mode of an alfalfa leaf interchange, that is, by adding right turn ramps and small loops on the 4 corners of the ordinary grade intersection, it is like an alfalfa leaf interchange in form. Because of its low engineering cost, flexible traffic organization, simple control mode, and high traffic efficiency, it has become one of the selection types of urban expressway–main road or main road–main road intersection. According to the geometric characteristics and traffic organization characteristics of the plane interchange, and the evaluation objectives of intersection operation efficiency, safety, environment, and other aspects, an index system based on five specific evaluation indicators is proposed, including traffic capacity, average vehicle delay, intersection safety, CO emission, and detour distance. To overcome the subjective or objective situations of the index weight in the process of a multi-index evaluation, the TOPSIS method is optimized by using combined weighting, and the traffic organization evaluation model of plane interchange based on combined weighting TOPSIS method is constructed. Taking the three traffic organization modes of the West Middle Ring Auxiliary Road and Xinghua West Street plane interchange in Taiyuan as an example, in continuous working days, traffic data are obtained through intersection flow direction investigation, point sample delay investigation, headway and speed investigation; VISSIM intersection simulation model is established; and the evaluation index values are obtained directly or indirectly. The advantages and disadvantages of various schemes are determined through the combined weighting–TOPSIS method proposed in this paper. The calculation results are compared with the actual situation, which verifies the rationality of the method. The result can provide theoretical support for the rational evaluation of the urban plane interchange traffic organization or the regional traffic organization scheme using this idea.