The invention discloses a suction retaining device used in the water channel field, which comprises a main body and an elastic sealing sleeve, wherein the main body is internally provided with a water channel and at least one air inlet hole; the water channel comprises a water inlet hole and a mutation cavity communicated with the water inlet hole, and the section area of the mutation cavity is greater than that of the water inlet hole; the air inlet hole comprises an air inlet and an air outlet, the air inlet is arranged outside the main body, and the air outlet is arranged in the mutation cavity; the elastic sealing sleeve is sleeved in the main body and fitted with the air inlet hole of the main body; in case the water in the water channel flows clockwise, a negative pressure is produced in the mutation cavity and the mutation cavity adsorbs the elastic sealing sleeve so as to conduct the air inlet hole for inhale; and in case the water channel flows anticlockwise, the hydraulic pressure of the water channel acts on the inner side face of the elastic sealing sleeve so as to enable the elastic sealing sleeve seal the water inlet hole.