The lightweight design of gears is a key focus in the development of gear transmission, and thin-rimmed gears represent an effective approach to achieving this goal. High-speed thin-rimmed gears find extensive and critical applications in engineering fields such as aviation. However, the centrifugal forces generated at high rotational speeds, along with the structure flexible of the thin-rimmed gear, can introduce a range of dynamic challenges to the transmission system. Therefore, a dynamic model is proposed to reflect the flexible characteristics of the thin-rimmed gear. First, the gear teeth are sliced along tooth width direction, and the meshing stiffness of each tooth slice in helical gears is calculated to determine the meshing forces and torques in the gear transmission. Subsequently, the reduced-order finite element (ROFE) model of gear body and the housing are established. By coupling these models, a dynamic model of the thin-rimmed gear transmission is established. Based on this, the study investigates the effects of structural flexibility and centrifugal forces and discusses methodologies for determining the manufacturing accuracy of the thin-rimmed gear.