<p> To address arbitrary parking slots for parking autonomous vehicles, a unified optimal plan-control method, which consists of a trajectory planner and tracking controller, was proposed in this paper. The trajectory planner consists of a reference path planner, a path smoother and a differential solver. Im-hybrid A* is developed to quickly search for the optimal reference path for arbitrary lots. A hierarchical arbitration strategy is designed to accelerate the rate of node validity arbitration and to avoid false detections. Both the path smoother of the trajectory controller and the motion controller of the tracking controller are designed based on model predictive control theory. The former is used to smooth the planned reference path to get the optimal trajectory, while the latter is used to track the optimal trajectory for parking the autonomous vehicle into the lot. Taking the standard into account, five kinds of regular parking simulation scenarios were designed and three kinds of real parking tests were developed to verify the proposed method. The simulation results illustrate that the unified optimal plan-control method has strong coverage for various lots specified by the standard. Meanwhile, the actual vehicle test results indicate that the proposed method can park the autonomous vehicle smoothly in the lot and maintain a good parking state.</p>