A tidal current energy generating device includes a generator, a connecting shaft, an impeller and an adjustment assembly. The impeller includes an impeller hub and an impeller blade arranged thereon. The impeller hub is connected with the connecting shaft, and the generator is connected with the impeller hub. The impeller blade is driven under the action of a tidal current to drive the impeller hub to rotate synchronously around an axis of the connecting shaft, driving the generator to generate electricity. The adjustment assembly is connected with the impeller blade, and can be driven to swing under the action of the tidal current to drive the impeller blade to rotate around the axis of the impeller blade relative to the impeller hub, thereby adjusting the angle of the impeller blade.