Abstract: To address the dynamics modeling of a single local damage fault in rolling bearings, a comprehensive approach based on Hertz contact theory has been developed.Specifically, a contact deformation retention factor is defined and a variable stiffness function using a static analysis method is proposed. This allowed us to establish and simulate a variable stiffness dynamics model for a single local damage fault in rolling bearings under radial load. The model was also experimentally validated. The research results show that when the rolling element enters the load zone its effective contact stiffness suddenly increases. Conversely, when it exits the load zone or falls into the fault position, the stiffness suddenly decreases. This change causes the contact force and contact deformation of other load-carrying rolling elements in the load zone to suddenly decrease or increase to rebalance the external load. However, this does not affect the effective contact stiffness of the rolling element itself. The effect is more pronounced for rolling elements near the center of the load zone. Additionally, these changes cause the total effective stiffness of the system to suddenly increase or decrease, leading to system vibrations. When the outer race has a fault, the change in total effective stiffness is of equal amplitude, resulting in an equal-amplitude time-domain vibration response. In contrast, when the inner race has a fault, both the change in total effective stiffness and the response amplitude are modulated by the rotation of the inner race, leading to significant variations. The proposed variable stiffness dynamics model is more consistent with reality and provides a certain theoretical basis for effective diagnosis of rolling bearing faults.