The invention belongs to the technical field of aero-engine design, and particularly relates to an interpolation method suitable for an aero-engine real-time model. The method comprises the followingsteps: firstly, recording an interpolation algorithm of a current rotating speed position, a current pressure ratio position and a current adjustable blade angle position and the slope; performing first interpolation according to the current rotating speed; obtaining four discrete points, carrying out second interpolation according to the current adjustable blade angle; obtaining two discrete points, and finally, carrying out third interpolation according to the current voltage ratio to obtain the flow and the efficiency of the current working point; recording the interpolation position and the slope of the previous period in the difference calculation process of the next working point, judging whether the position value and the slope value need to be updated or not. Repeated circulation caused by searching is reduced, the interpolation efficiency in a real-time model is improved, and the real-time model running speed is increased.