A liquid rationing device comprises a base and a cover. The base is provided with an actuating element whose axle goes through the base. The axle is connected with a gear disk, which is provided with more than one roller on one side thereof. The cover is coupled to one side of the base and has a reservoir provided with a transmission hose with positioning extrusion. A positioning groove is provided on the reservoir such that the positioning extrusion of the transmission hose can be held therein and the transmission hose can surround the circle of the rollers. Accordingly, the actuating element can drive the gear disk and make the rollers on the gear disk to rotate and subsequently push and squeeze the transmission hose, thereby making displacement of the liquid in the transmission hose and obtaining the purposes of rationing.