Abstract: To address the issue of matching lost circulation materials with dynamic fractures during plugging operations, based on the 1/3-2/3 bridging rule and considering the amplitude of dynamic fracture width, a reference fracture width for particle size screening was determined. A mathematical model for optimizing the particle size of lost circulation materials based on dynamic fracture width was established, and a stability criterion for key bridging particles was proposed. The factors influencing bridging stability were analyzed, and the plugging capability of the optimized particles was verified through simulation experiments. The results show that when the maximum fracture width increases from 3.5 mm to 4.2 mm, the maximum bridging particle size increases from 1.75 mm to 2.10 mm, while the minimum fracture width determines the upper limit of the bridging particle size. The bridging particle size increases with the maximum fracture width. When the maximum bridging particle size equals the minimum fracture width, there is a risk of bridging-off. When the amplitude of dynamic fracture width exceeds 50%, bridging particles cannot form a stable bridge within the fracture, necessitating alternative plugging techniques. The lost circulation material system optimized by this model can accommodate a dynamic fracture width amplitude of 37%, achieving a pressure bearing capacity of 9.8 MPa and a cumulative fluid loss of 93 mL in dynamic fracture experiments, outperforming traditional static bridging rules. By accurately quantifying particle sizes under dynamic fracture conditions, this model significantly improves dynamic plugging performance. The findings provide a theoretical reference for optimizing the particle size and proportioning of lost circulation materials in field applications.