In order to obtain better control effects, Integer-order model is used as the research object, a fictitious fractional-order model is introduced to design the original control system and the optimal orders of the chosen fractional-order are determined by a defined control performance index. Using the same out put variable to build the relationship between fractional-order system and integer-order one, a control strategy based on systemic output is implemented to ensure the designed controller can be used for the original integer-order model. The simulation result shows that the order affects both the control effect and the stability of the control system. Finally, an example is given to illustrate the feasibility of the proposed control strategy.