The Enterprise Service Bus system which is based on Stage Event-Driven Architecture is divided into five stages according to the logic processing functions: message listener, protocol analysis, message exchange, message route and message send. During the system running, the central scheduler collects states of these stages' information. This research adjusts thread pool size of each stage dynamically based on the mean-variance analysis, then all stages' task processing ability are associated, which can avoid some stages' heavily burden that may affects the performance of entire system.