The invention provides a modeling method of the transient process of an aero-engine, and belongs to the field of modeling and simulating of the transient state of the aero-engine. By distinguishing a dynamic model of the aero-engine in different steady states and combining the dynamic model with a corresponding steady-state model, the transient process of the aero-engine is presented as a dynamic variable parameter model through methods of polynomial fitting and a least squares support vector machine. The approximate transient process of multiple discrete steady state points is improved, the dynamic characteristics are better, and the situation that by means of an existing method, error accumulation exists when modeling of the transient state is conducted through output accumulation is improved; meanwhile, single input multiple output is modeling through the method, universality is wider, modeling can be promoted to modeling of the transient process of multiple input multiple output aero-engine through proper adjustment.