In the multi - stage fracturing process of shale gas horizontal wells, the fracturing fluid may connect with faults through artificial fractures, triggering fault activation and subsequent slip, which in turn leads to casing deformation. Taking Lu208X Well as an example, this paper establishes a calculation model for fault slip considering the changes in formation pore pressure induced by fracturing. A sensitivity analysis of the factors influencing fault slip is conducted, and it is determined that the increment of pore pressure during fracturing is the primary controlling factor for fault slip. The research findings indicate that during and after the fracturing process, the friction coefficient of the fault continuously decreases, posing a risk of an increase in fault slip. The length and dip angle of the fault are closely related to the amount of fault slip. Specifically, the greater the fault length, the larger the amount of fault slip. Within a certain range, the larger the fault dip angle, the larger the amount of fault slip. A formation with a high elastic modulus exerts a strong constraint on the fault, resulting in a smaller amount of fault slip. Poisson's ratio has a relatively minor impact on fault slip. These research results can provide a basis for optimizing the construction parameters of multi - stage fracturing in shale gas horizontal wells.