The invention relates to a visualization experiment device for simulating temporary plugging of hydraulic fractures by a fiber diversion agent. A pipeline is communicated with the upper end of a simulating shaft steel tube with the lower end sealed, the pipeline is connected with a first high-pressure plunger pump, and the first high-pressure plunger pump is communicated with a liquid storage tank. The pipeline is connected with a fiber adding device through a branch pipeline, and the fiber adding device is connected with a second high-pressure plunger pump. Through holes are formed in the pipe walls on the two sides of the simulating shaft steel tube respectively, a connected body is fixed to the position corresponding to the through hole in each side, the first ends of the two connecting bodies are connected with the side wall of the simulating shaft steel tube in a sealed mode, the second end of the connecting body on each side is connected with a visualization hydraulic fracture simulating device in a sealed mode. The hydraulic fractures are formed in the end faces, connected with the second ends of the connecting bodies, of the visualization hydraulic fracture simulating devices, and liquid flow channels are formed in the connecting bodies. The visualization experiment device is simple in structure and convenient to operate, and technicians can visually observe the temporary plugging depth, the form and other information and the plugging effect of temporary plugging of hydraulic fractures by the fiber diversion agent.