The invention belongs to the technical field of hydraulic gates, and particularly relates to a large-size hydraulic gate with an auxiliary function of opening and closing. The large-size hydraulic gate comprises a portal frame, a gate body and a hoist, wherein one end of the hoist is provided with a driving motor, the other end of the hoist is provided with a manual rotation handle, an auxiliary power gear box is arranged between the hoist and the driving motor, one of the sides of the bottom of the portal frame is provided with a horizontally placed U-shaped supporting frame, the U-shaped supporting frame is internally provided with a water wheel, the portion from one of the ends of the water wheel to the exterior of the U-shaped supporting frame is connected with a worm and gear structure, the worm and gear structure is provided with a vertical first driving shaft, the auxiliary power gear box is provided with an active input shaft, an auxiliary power input shaft, a transmission shaft, a one-way transmission gear box and a power output shaft, the active input shaft is connected with the driving motor, the auxiliary power input shaft is connected with the first driving shaft, andthe power output shaft is connected with the hoist. The large-size hydraulic gate has the advantages that the deficiencies in the prior art are overcome, the power consumption is effectively reduced,the energy-saving effect is good.