Aiming at the fair and efficient bandwidths allocation for the geographically distributed control systems, a distributed and dynamic bandwidth allocation algorithm was proposed.Firstly, the bandwidth allocation problem was formulated as a convex optimization problem, namely, the sum of utilities of all the control systems was maximized. Further, the idea of the distributed bandwidth allocation algorithm was adopted to make the control systems vary their sampling periods based on fed-back congestion information from the network, and get the maximum sampling rate or maximum transmission rate which could be used. Then the interaction between control systems and links was modelled as a time-delay dynamical system, and Proportional-Integral (PI) controller was used as the link queue controller to realize the algorithm; The simulation results show that the proposed bandwidth allocation algorithm can not only make the transmission rates of all plants converge to the value where all plants share the bandwidth equally in 10 seconds. At the same time, for the PI controller, its queue stabilizes around the desired set point of 50 packets, and can accurately and steadily track the input signal to maximize the performance of all control systems.