Abstract: An attitude adjustment apparatus for a self-propelled bio-inspired robotic fish includes a fish body, where the fish body includes: a housing; a center-of-gravity adjustment assembly, located in the housing to adjust a center of gravity of the fish body, and including at least one counterweight and a screw-slider mechanism that drives the counterweight to move in a head-to-tail direction; and a suction and drainage system, located in the housing to adjust a weight of the fish body, and including a ballast tank and a water control assembly for controlling a water level in the ballast tank. The center-of-gravity adjustment assembly is combined with the suction and drainage system to rapidly change the weight and center of gravity of the fish body, so as to quickly adjust the pitching attitude and heaving state of the robotic fish.