Multilayer polycrystalline diamond compact and preparation method thereof

The invention relates to a multilayer polycrystalline diamond compact and a preparation method thereof, and belongs to the field of diamond compacts. The multilayer polycrystalline diamond compact comprises a hard alloy matrix, a polycrystalline diamond layer, a tungsten carbide composite material layer and a hard alloy protection layer which are sequentially arranged from bottom to top, wherein the tungsten carbide composite material layer is prepared from the following raw materials in percentage by weight: 95-97% of tungsten carbide powder and 3-5% of metallic bond. According to the multilayer polycrystalline diamond compact provided by the invention, a plurality of layers of different types of materials and a hardness gradient structure are designed, the chemical stability of tungsten carbide and the high strength and wear resistance of diamond are utilized, good transition to the polycrystalline diamond layer is formed in physical properties, and the two sides of a material layer at the middle part are protected, so that the multilayer polycrystalline diamond compact is capable of effectively reducing the residual stress of the hard alloy matrix and the polycrystalline diamond layer, increasing the abrasive ratio of the diamond compact, and improving the impact toughness and bending strength.