The invention belongs to the technical field of construction of hot-dry rock artificial geothermal reservoirs, and particularly relates to a method for building a hot-dry rock artificial geothermal reservoir by using natural geological faults. The method comprises the following steps that 1, the occurrences, the number and the sizes of the faults in a hot-dry rock geothermal development area are determined; 2, a well group is arranged and designed along the trend of the target fault, wherein according to the arrangement way of the well group, shafts are linearly arranged in a one-injection-two-return way; 3, an injection well is drilled in the center of the trend of the target fault; 4, in the combination of the geophysical prospecting imaging technology, the macro-size of a large-fault and the azimuthal angle of a drilling hole are determined, and according to the macro-size and the azimuthal angle, the occurrence of the target fault can be precisely determined; 5, the target fault and near fracture zones are used as the fracture development artificial geothermal reservoir which is high in permeability and large in heat exchange area; 6, a lot of room-temperature water is injectedinto the injection well, heat exchange is conducted through the natural artificial geothermal reservoir crack network of the target fault, transformation from solid heat to liquid heat is achieved, and high-temperature water and over-hot water vapor are produced from production wells to be used for electricity generation or heat supply.