In order to further improve the control precision of Autonomous Underwater Vehicle (AUV), a six-degree-of-freedom fully actuated AUV is modeled and a corresponding Active Disturbance Rejection Controller (ADRC) is developed. Considering that the traditional ADRC requires excessive parameter tuning and necessitates corresponding adjustments as the system operates, in response to this, a novel approach based on Pigeon-Inspired Optimization (PIO) is proposed to optimize the ADRC. Under the same simulation conditions, the control effectiveness of the PIO-ADRC is compared against that of the Pigeon-Inspired Optimized Proportional Integral Derivative (PIO-PID) controller and traditional ADRC. The results indicate that the ADRC optimized with PIO algorithm exhibits smaller overshoot, reduced steady-state error and higher control efficiency.