Abstract: This paper proposes a dynamic tracking method based on the relative curvature relationship between the tractor and the trailer trajectory to address the trajectory tracking problem of the trailer in tractor-trailer wheeled mobile robot with an off-axle hitching.First，the kinematics model and dynamics model of the tractor-trailer wheeled mobile robot with an off-axle hitching are built.Then，the speed relationship between the two vehicles is determined with the aid of the geometric relationship between the tractor and the trailer position，and the relationship between the relative curvatures of the two vehicles’trajectories is obtained.Based on the curvature relation，the motion task of the tractor is transformed into the motion task of the trailer，and a proportion integration feedback controller is designed to complete the motion task of the tractor by combining with the dynamic tracking method.Finally，the accurate trajectory tracking control of the trailer is achieved by simulation.Our simulation results show the trailer accurately tracks the target trajectory curve under the action of the proposed controller.As our dynamic tracking method introduces the relative curvature of the target trajectory curve，the tracking accuracy is substantially improved.