The invention discloses a digital imaging device for a fault of an indoor earth-rock aggregate sample and a three-dimensional numerical value reverse reconstruction method, and belongs to the field of testing equipment. The device comprises a fixing mechanism, a polishing mechanism, a precession mechanism and a detection mechanism. The method comprises the following steps: exposing a two-dimensional stone shape of the fault in the earth-rock aggregate sample layer by layer through the polishing mechanism, acquiring two-dimensional shape information of a stone of the exposed fault layer by layer through a digital camera at the top part, acquiring the two-dimensional shape information of the fault of the whole earth-rock aggregate sample, and reversely constructing a three-dimensional numerical value model of the earth-rock aggregate sample through MATLAB software programming. Compared with the traditional way of acquiring the information of the fault of the earth-rock aggregate through CT scanning, the method provided by the invention has the advantages that the cost of the device is low, the operation is simple and flexible, the device is freely disassembled and assembled, the field adaptability is wide, and the device can be vertically or horizontally distributed, is suitable for the reverse reconstruction of the earth-rock aggregate samples in various sizes, and has no weight restrictions.