A rock mass engineering cross-scale simulation calculation method based on REV all-region coverage, including establishing a rock mass engineering scale calculation model of particles and joints, and providing the model with particle material parameters and contact parameters; performing model region division dividing the model into multiple finite elements, and performing all-region coverage and mesh division using the finite elements, wherein a volume of the finite element is equal to a representative elementary volume of a REV model; and applying boundary conditions, calculating force and motion information of finite element nodes using a continuous medium method, obtaining a failed finite element according to the node force and motion information, and calculating motion information of particles of the REV model in the failed finite element using a discontinuous medium method. According to the calculation method, the calculation efficiency is improved, and the accuracy of calculation results is ensured.