Abstract: Aiming at the problem in which a vessel's dynamic positioning system can control it at an expected position, a novel linear active disturbance rejection controller is designed to solve the problem of poor dynamic performance due to the omission of a tracking differentiator. Based on the advantages of linear and nonlinear tracking differentiators, an improved tracking differentiator is designed which can track the differential signal and degrade the effects of noise; it constitutes a novel Linear Active Disturbance Rejection Controller (LADRC). The simulation results show that the novel LADRC based on the improved tracking differentiator has strong robustness, high control accuracy and good dynamic performance compared with the traditional LADRC.