Abstract: The fatigue test of simulation specimen provides an important reference for the fatigue strength design of aeroengine disc. In order to simplify the design process of simulation specimen and form a standard design system, this paper proposes a design method of simulation specimen for eccentric holes and tenon-grooves of aeroengine discs based on the theory of critical distance (TCD), according to the principle of similarity of stress concentration factors and stress gradients. The form of the simulation specimen in this paper is a round bar with an annular groove. The influence of different notch size on von-Mises stress distribution along the radial direction of notch root is analyzed by using finite element method, and the normalized stress distribution parameter formula is fitted. Simulation specimens of eccentric hole and tenon-groove of an aeroengine disc are designed. The similarity between the simulation specimen and the disc is more than 90% in stress concentration factor and stress gradient within the critical distance. The strain field distribution of the simulation specimen is obtained through 3D-DIC to verify the design of the simulator.