The present invention provides a lotion pump, comprises: a nozzle head; a plunger connected with the nozzle head, in which an upper one-way valve is disposed; a container cap which is engaged with a mouth of a bottle; a housing, its upper end is connected to the container cap, and on its lower end there is a lower one-way valve; and a spring, its lower end abuts against the bottom of the housing, and its upper end abuts against the head of the plunger; characterized in that, the diameter of an upper portion of the plunger is larger than that of a lower portion of the plunger, thereby a step is formed at the position where the diameter is changed, said step forms a valve seat for said upper one-way valve. The lotion pump of the present invention can be realized by a very simple structure, minimum parts and a very low manufacturing cost. While greatly increasing the productivity, it can obtain good sealing and leak-proof performance.