Abstract: Differential robots exhibit superior flexibility and scalability compared to other types of robots. Addressing the issue of reduced precision in path tracking control due to constraint coupling in differential robots, this study employs Nonlinear Model Predictive Control (NMPC) as the foundation. By analyzing the coupling relationship between the longitudinal velocity of the differential robot and the reference path coordinates within NMPC, we propose an NMPC-based active speed regulating path tracking for differential robots under the influence of constraints coupling, achieving proactive dynamic adjustment of the differential robot's velocity. To validate the proposed control method, Simulink simulations were conducted. The results demonstrate that the motion control system enhances the precision of differential robots in path tracking control, with the absolute value of simulated displacement error not exceeding 0.0723 m and the absolute value of heading error not exceeding 0.0964 rad. Compared to the constant speed path tracking control system, the proposed system can reduce the maximum amplitude of displacement error by 99.22% and the maximum amplitude of heading error by 93.32%. Meanwhile, compared with the existing active speed regulating path tracking control system, it is able to reduce the maximum magnitude of displacement error and the maximum magnitude of heading error by 87.54% and 29.69%.