The use of degradable polymer materials as controlling additives to the working fluid during hydraulic fracturing is an area of interest in developing stimulation technologies. A temporary plugging agent with high compressive strength is used to block pre-fracturing or natural cracking and to initiate new fracture joints in order to increase the oil and gas passages, thereby realizing a stable production of oil and gas reservoirs. The temporary plugging agent prevents the fluid from entering the existing cracks, allowing the fracturing fluid to create new cracks and a more complex network of fractures within the reservoir. Considering the technological requirements, the temporary plugging agent must have a strong pressure resistance, good water solubility, and good returning performance, which can make new and old cracks simultaneously effective. In this paper, a new type of internal temporary plugging agent is developed, and the temporary plugging mechanism is evaluated through experiments, including plugging material microstructure, particle size, water absorption, water absorption speed, temporary plugging effect, and conductivity after dissolution. Our study shows that the temporary plugging agent provides a good temporary plugging effect, causes no pollution to the oil well, and can play a good protective role on the reservoir in repeated fracturing.