The invention relates to a pre-applied shearing strength test piece, a preparation device and a preparation method for a test piece and a splitting test method. The invention aims to overcome the defects that only a single-axial tensile pressing condition is considered and the shearing strength is difficult to consider on the basis of the traditional high pressure water splitting simulation test design method and traditional high pressure water splitting simulation test design device and the test piece only can be normal concrete. The test piece has an extending direction; an inclined layer is arranged on the middle position along the length direction of the extending direction; an included angle alpha is formed between the inclined layer and a preset direction; a preset crack is arranged on the inclined layer; the preset crack is communicated with the exterior of the test piece through an interface channel. According to the test method, the preset crack is filled with high pressure water till the preset crack is split and a single-shaft test device is used for applying the shearing strength to the test piece. The test piece, the device and the test method provided by the invention can consider the influence of the shearing strength of the roller compacted concrete, so that the working condition of the roller compacted layer of a roller compacted concrete high-dam under the effect of high pressure water can be effectively simulated.