Taking the XY motorway PPP project as the research object, we construct a multi-level comprehensive evaluation index system for private sector partners of PPP projects, determine the weights of the evaluation system by using the deviation maximisation weighting, and carry out the final evaluation and decision-making analysis of the private sector based on the superiority and inferiority solution distance model. This paper defines the essential connotation of private sector consortium formation in infrastructure PPP projects, establishes a multidimensional data integration decision-making framework based on the combination of deviation maximisation and TOPSIS, and empirically tests the scientificity and applicability of the model. It provides scientific and operable methodological guidance for the formation of private sector consortia, and provides theoretical support for the landing and sustainable development of the PPP mode.