The invention discloses an adaptive motion control device and method of an underwater robot. The device comprises an inner loop control module and an outer loop control module; the outer loop controlmodule tracks desired signals; the inner loop control module tracks the virtual control law of the outer loop control module; a disturbance compensation item and an input uncertainty compensation itemare added to the outer loop control module; the outer loop control module constructs a nonlinear adaptive compensation module based on the fuzzy logic of a fuzzy logic module and the dynamic signalsof a dynamic signal generation module; an actuator nonlinear module is constructed based on the nonlinear adaptive compensation module; an underwater robot dynamics model is constructed based on the actuator nonlinear module; and an underwater robot kinematics model is constructed based on the underwater robot dynamics model. With the adaptive motion control device and method of the underwater robot of the invention, it can be ensured that the underwater robot can realize desired trajectory and attitude tracking in an underwater complex environment, and at the same time, non-linear characteristics such as dead zones existing in an actuator can be well processed.