An event-triggered model predictive control (MPC) algorithm is proposed to solve the obstacle avoidance problem of autonomous underwater vehicle (AUV) formation in complex environment. Tablishing a motion model of the AUV, combining a leader-follower formation control method, and obtaining the navigation track and speed information of a virtual AUV by using the position information of the leader AUV and an expected formation of the formation, and taking the navigation track and the speed information as the navigation reference track of a following AUV; The traditional artificial potential field (APF) method is improved adaptively to meet the needs of AUV formation obstacle avoidance planning in obstacle environment; An event-triggered mechanism based on the error between the predicted and actual values of the following AUV trajectory is designed to reduce the amount of calculation for solving the optimization problem and reduce the computational burden. The simulation results show that the proposed algorithm is feasible and effective compared with other algorithms.