Based on the introduction of the composition and operation principle of the single variable electro-hydrostatic actuation system of the main flight control surface, this paper puts forward the dynamic characteristics and stability index requirements of the electro-hydrostatic actuation system, and establishes its simulation model, as well as analyzes the dynamic characteristics and stability index of the system from the aspect of time domain and frequency domain through a large number of numerical simulation so as to summarize influence factors respectively. The research results of this paper provide reference for the design of the electro-hydrostatic actuation system and guarantee to design an such a system with the excellent performance.