The invention relates to a 
turbofan engine 
steady state transition state multivariable control method based on a self-disturbance rejection theory, and belongs to the technical field of aero-engine control. The 
turbofan engine 
steady state transition state multivariable control method comprises the following steps that firstly, the control quantity and the controlled quantity of a plurality of sets of 
turbofan engines are preliminarily selected, then a 
correlation analysis method is used for further determining the control quantity and the controlled quantity which are relatively large in correlation; a tracking 
differentiator is adopted for planning each group of control instructions into a tracking track, then is taken together with the current state estimated by the expansion 
state observer to serve as an input of the nonlinear proportional-differential controller an input calculation control amount for nonlinear proportional-differential controller, meanwhile, a proper structure isused for offsetting the expansion 
state observer to observe the total disturbance including the 
coupling among the multiple variables, so that a 
good control effect is achieved. According to the turbofan engine 
steady state transition state multivariable control method, multi-input multi-output of turbofan engine requirement is met, meanwhile, target for control requirements is achieved accordingto preset trajectory operation, compared with the design method of a traditional control controller, the difficulty is smaller, the number of parameters needing to be adjusted is small, the physicalsignificance is very clear, and the robustness of the 
system is greatly improved.