The invention belongs to the technical field of grouting engineering of fractured rock mass, and discloses a method for identifying a diffusion range of fracturing grouting in fractured rock mass based on microseismic monitoring. The method comprises the following steps that: slurry is loaded in cracks of the rock mass for flowing and diffusing with a grouting pressure during grouting; a diffusionstress acts on inner walls of the cracks to cause injuries and damages to the fractured rock mass, which leads to energy release generated by the rock mass; especially for high pressure fracturing grouting, energy release is intensive and microseismic events are obvious; and a microseismic monitoring system is used to capture and identify energy release points and combines with a test sampling todetermine good and bad events so as to realize real-time calibration of the slurry diffusion and an influence range, which is conducive to implementation of the grouting operation. The method for identifying the diffusion range of the fracturing grouting in the fractured rock mass based on the microseismic monitoring can realize the determination of the slurry diffusion and its influence range inthe grouting engineering, and realize safe, efficient and low-cost application of the grouting technology in a wide range of fields.