The invention provides a rock sample machining method and device for a true-triaxial fracture physical simulation experiment of a tilted stratum. The method comprises the steps that shale outcrop is machined into a cubic rock sample in the parallel bedding plane direction and the vertical bedding plane direction; waterproof treatment is carried out on the cubic rock sample, so that a waterproof rock sample is formed; fixing slurry of a preset volume is injected into a mould, then the waterproof rock sample is placed in the mould with the bedding plane of the waterproof rock sample parallel to the vertical direction, and the rock sample is rotated by a preset angle; the fixing slurry continues to be injected into the mould till a cavity of the mould is filled with the fixing slurry; the mould is detached after a first preset duration, and the rock sample wrapped with the fixing slurry is obtained; and the blind hole drilling direction is determined on the rock sample wrapped with the fixing slurry, and blind holes are drilled. The finally obtained rock sample wrapped with the fixing slurry can be used for implementing the true-triaxial fracture physical simulation experiment of the tilted stratum, and moreover, the success rate of rock sample machining is increased.