The invention discloses a space engine-driven tail swing propelling plant which comprises a K-H-V type linear hypocycloid planetary gear train, a planetary plate external plate rotating device, a space ball accessory rod system, an engine-driven control mechanism and a tail fin direction control mechanism. The K-H-V type linear hypocycloid planetary gear train and the space ball accessory rod system comprehensively act to achieve swing/flapping of the tail of a robotic fish. The planetary plate external plate rotating device drives a planetary plate to rotate. The swing/flapping movement direction of a tail fin connection rod is changed by changing the position of a movement output point on a planet gear on a planet gear dividing circle. The engine-driven control mechanism drives a movable rack to rotate to achieve turning maneuver and rising and submerging of the robotic fish. The tail fin direction control mechanism controls the water striking angle of the tail fin to keep the tail fin at the optimal water striking angle. By means of the space engine-driven tail swing propelling plant, free switching between carangidae mode swimming and dolphin mode swimming is achieved, the mechanism principle and structural composition are simple, the tail fin movement is free of quick-return, and the space engine-driven tail swing propelling plant is suitable for being applied to power devices of automatic underwater crafts.