The invention provides a brake block for a high-speed train and a preparation method thereof, which belongs to the technical field of powdery metallurgical materials and is used for solving the problem of unstable friction factor of a semimetal-based composite brake block. The improved brake block is made from the following powdery raw materials according to parts by weight: 25 to 55 parts of copper powder, 5 to 20 parts of nickel powder, 4 to 12 parts of iron powder, 1 to 4 parts of manganese powder, 1 to 9 parts of chromium powder, 5 to 20 parts of graphite, 5 to 10 parts of carborundum, 1 to 8 parts of tungsten powder, 3 to 6 parts of titanium pigment, 3 to 10 parts of silicon dioxide, 1 to 4 parts of titanium powder, and 1 to 5 parts of aluminum powder. The raw materials are technically pure, and the grain size is 200 meshes or less. The brake block is made from metal-based composite raw materials, the raw material of the substrate is copper alloy with high thermal conductivity and good plasticity. With the reasonable adoption of other materials and optimized proportioning thereof, the made brake block has the following characteristics: 1. base body with good thermal shock resistance and no crazing, 2. stable change of friction factors under the condition of friction temperature rise, and 3. low attrition rate and long service life.