Abstract: [Objectives] Aiming at the influence of multi-source disturbances such as the environmental loads, the bank effects, the model uncertainties and the control allocation errors encountered during the autonomous berthing of ships. [Methods] A null-space-based active disturbance rejection control allocation method is proposed. Firstly, the ship berthing motion model, multi-source disturbances model and control allocation model are established, and a neural network extended state observer (ESO) is designed to estimate ship states and multi-source disturbances in real time. Secondly, the null-space technology is introduced to design the control allocation algorithm, and based on this method, the scheme of stabilization control outside the berth and then parallel berthing is realized. Finally, it is proved that all error signals of the autonomous berthing system under the proposed method remain uniformly ultimately bounded, ensuring the safety of the autonomous berthing process. [Results] The comparative simulation results show that the proposed method has a trajectory tracking effect similar to that of the quadratic programming (QP) method, and the solution time required is about 1.3%, and the yaw maximum allocation error is 36.51% of the pseudo inverse (PI) method. [Conclusions] The proposed method not only ensures the accuracy of berthing motion control, but also significantly reduces the time required for solving and the maximum allocation error. This ensures real-time control allocation with high accuracy.