Fine-grained permission change method, device and system for data hierarchical access

The invention relates to the technical field of data access control, in particular to a fine-grained permission changing method, device and system oriented to data hierarchical access. According to the method and the device, authority change is carried out based on the threshold node change number, and in the change process, the authority change is divided into a single-threshold scene and a multi-threshold scene, so that change request full coverage of fine granularity is realized, and multi-threshold node change is realized. The method specifically comprises strategy epitaxy and strategy reduction situations, strategy epitaxy is carried out when a plurality of threshold nodes need to be added to form a new strategy, and strategy reduction is carried out when the plurality of threshold nodes are deleted on the basis of an original strategy. When a single threshold node is changed, an attribute regulation and control mode is adopted, namely, when authorization change only relates to a single threshold node, u