An integrated active steering control strategy for tractor and trailer unit of articulated vehicles is presented in order to achieve both autonomous and safe motion. The tractor and trailer controllers are designed to preview and follow the demanded path automatically and safely. Based on model predictive control (MPC) theory, the integrated active steering controller of the tractor and trailer is designed to minimise path-tracking deviation while taking lateral stability into account. The manoeuvrability and stability of the articulated vehicle under the proposed control strategy are verified by simulations at low speed and high speed, respectively. The results confirm that the proposed integrated active steering system is capable of keeping the articulated vehicle automatically following the demanded path with high stability. The lateral stability and path-tracking of both tractor and trailer are significantly improved.