The performance improvement is closely related to the energy-saving operation of urban rail transit system and the improvement of service quality, which involves the optimization of infrastructures, the application of advanced train control technology, the highly efficient transportation organization, and the recycle and utilization of regenerative energy, etc. With the energy consumption as an entry, we first discuss the performance of urban rail transit system, determinate the corresponding performance evaluation indexes, and establish the top-down decomposition architecture of global performance. Then, we analyze the performance emergence mechanism of urban rail transit system, and build the difference equations of calculating train behavior in the constant power and natural characteristic regions and the mathematical model of train behavior optimization. The simulations are used to analyze the influence of train light-weighting, train control, and the load ratio on the energy efficiency of train operation, which can help to improve the system performance. Finally, we discuss the recycle and utilization of regenerative energy generated from train braking, the energy-saving operation of the environment control systems, and the optimization of train stop scheme, etc. The research shows that the potential of improving the performance of urban rail transit system is enormous, and deserves more attention. (C) 2018 Elsevier Ltd. All rights reserved.