The invention relates to a method for making a building material by using a city waste material. The method comprises the following steps: a) uniformly mixing the components in parts by weight: 20-30parts of cement, 10-12 parts of concrete block, 10-12 parts of crushed bricks, 5-8 parts of red mud, 20-30 parts of fly ash, 10-20 parts of waste board, and 5-8 parts of asbestos, and then breaking amixture; b) adding water in the mixture, uniformly stirring the materials to form a mixed slurry; c) loading a die with the mixed slurry, and performing pressurization to produce hollow brick casing;and d) filling the hollow brick with a soft material, sealing with a fly ash slurry, and forming the brick finished product. The building material takes city garbage such as concrete block, the crushed bricks, red mud, fly ash, waste board and asbestos as main raw materials, steps of crushing, mixing, loading, filling, and sealing are carried out, the brick can be produced, the city garbage is effectively used, waste can be used, energy saving and environmental protection are realized, and the produced brick has the advantages of light weight, little thickness, water resistance, and sound insulation.