The invention relates to a centrifugal impeller boss crack propagation feature simulator design method. The method comprises the following steps: acquiring a geometric model of a centrifugal impeller,measuring a transition fillet semi-diameter of a boss structure and a boss radial length; acquiring a working condition of the centrifugal impeller and the material performance parameter under the working condition; establishing a centrifugal impeller finite element analysis model, computing to acquire the stress maximum point of the boss part of the centrifugal impeller; taking the rectangular slab test piece as the basic shape, wherein boss structures are arranged on symmetric locations at two sides of the slab, and the transition fillet semi-diameters of the boss and the rectangular slab and the boss radial length and the actual structure are consistent; enabling the maximum stress at the stretching direction of the simulator close to the boss location is consistent with the actual structure by adjusting the test piece length method, and guaranteeing that the stress gradient is same; checking the relation of the stress strength factor of the simulator and the test piece thickness,determining the thickness of the test piece, wherein the obtained simulator can simulate the stress strain field of the centrifugal impeller boss structure and can be used for developing crack extension test.