Abstract: The development and application of mobile energy storage technology inspires new ideas and methods for peak load shifting in distribution networks. Based on the time-space flexibility of the mobile energy storage system（MESS） to provide charging and discharging services, a bi-level optimal dispatch scheme that comprehensively considers the reliability and economy of peak load shifting is proposed. Firstly, a bi-level optimal dispatch model of peak load shifting for mobile energy storage is established, and the upper layer takes the minimum equivalent load standard deviation and the highest net income as the optimization goals, and aims to reduce the peak-to-valley load difference and realize the price arbitrage. The lower layer takes the minimum network loss as the optimization goal and aims to determine the optimal dispatch strategy for mobile energy storage.Then, a solution algorithm for optimal dispatch which is suitable for the peak load shifting for mobile energy storage, is developed.In order to adapt to the high dimensional nonlinear characteristics of the lower model, an improved enhanced fireworks algorithm（EFWA） based on Cauchy and Gaussian mutations is proposed. Finally, the IEEE 33-bus system and the actual load data of a certain area are used for simulation analysis. The results verify the effectiveness and feasibility of the proposed model and solution algorithm.