The invention discloses a trajectory tracking control method of an underwater inspection robot. The method comprises the following steps: (1) presetting a reference trajectory for trajectory trackingof the underwater inspection robot, obtaining an optimal path from a starting point to a target point by using a navigation path planning algorithm according to the reference trajectory, and taking the optimal path as a preset reference trajectory of trajectory tracking of the robot; (2) designing a trajectory tracking kinematic controller in combination with the reference trajectory and a kinematic model; (3) carrying out stress analysis on the underwater inspection robot, establishing a dynamic model, and designing a trajectory tracking dynamic controller; and (4) taking a control value of the kinematic controller as input of the dynamic controller to obtain a thrust and a torque required by trajectory tracking, and realizing smooth and stable trajectory tracking control of the underwater inspection robot. By designing a dynamic target function, a problem of speed jump is solved, a lag between an actual trajectory and the reference trajectory is reduced, the shortest tracking step length optimization function item is added into the target function, the path length of the actual trajectory is reduced, and then trajectory tracking energy consumption is decreased; in addition, the influence of the actual underwater environment on trajectory tracking is also considered, and finally smooth and stable trajectory tracking control is realized.