Abstract: Shale reservoir hydraulic fracturing is a complex fluid solid coupling physical process. During fracturing, the infiltration of high-pressure fluid in the wellbore can induce the germination of microcracks in the surrounding rock of the wellbore, thereby affecting the rock initiation pressure. In order to explore the micro response characteristics and law of the surrounding rock of the wellbore during shale fracturing, hydraulic fracturing tests were conducted on shale under different confining pressures. Sensitivity analysis was conducted through numerical simulation, considering factors such as confining pressure, wellbore diameter, wellbore fluid pressure, Young's modulus, Poisson's ratio, and tensile strength of the rock on the plastic damage characteristics of hydraulic fracturing rock, The research results indicate that: ① confining pressure has a significant impact on the fracture pressure of shale hydraulic fracturing. The fracture pressure of shale hydraulic fracturing increases with the increase of confining pressure, and the fracture pressure obtained from experiments is higher than the theoretical value calculated by traditional models; ② During shale hydraulic fracturing, high-pressure fluid in the wellbore can cause microstructure damage to the surrounding rock of the wellbore. Based on numerical simulation, the existence of a plastic zone on the hydraulic fracturing wellbore was determined ; ③ The range of plastic zone on the wellbore during shale hydraulic fracturing is greatly influenced by rock reservoir conditions and construction parameters. Specifically, the size of the plastic zone is less affected by the Young's modulus and Poisson's ratio of the rock, and is positively correlated with wellbore diameter and internal fluid pressure, while negatively correlated with confining pressure and rock tensile strength. ④ At the scale of on-site engineering, the plastic zone of shale hydraulic fracturing presents an elliptical distribution, and the major axis is in the direction of the maximum horizontal principal stress. The research results have important theoretical and practical significance for predicting the fracturing pressure and fracturing construction design of deep rock hydraulic fracturing.