The over-temperature situation happened in summer will result in high-pressure failure in subway trains, so the highest tunnel temperature is an essential factor for safe operation. In this study, simulation method was adopted in factor-analysis. The three influencing factors concerning internal heat generation (passenger number, carriage weight, and Regenerative Braking System (RBS) efficiency), and two factors concerning transmission load (soil conductivity and thermal capacity) were analyzed. Based on a serial of orthogonal experiments, a Response Surface Model (RSM) of the subway tunnel temperature was established. This model provide a quick way of predicting subway tunnel temperature in different situations, which could be helpful in both design and operation stages in subway without complex and time-consuming simulations.