Mobile energy storage (MES) is vital for enhancing distribution network resilience and reliability. This paper proposes an optimal MES configuration method for multi-scenario emergency demands. First, a maximum emergency supply capacity model is developed considering flexible MES integration, followed by a spatio-temporal scheduling strategy. Second, an MES benefit model and a life-cycle cost model considering spatio-temporal scheduling are established respectively. To address peak loads and contingencies, a multi-stage capacity configuration and scheduling method is proposed to facilitate multi-scenario emergency multiplexing. Case studies demonstrate that this approach leverages MES’s flexible scheduling potential, effectively ensuring emergency supply while maximizing utilization and profitability.