The invention discloses a liquid chlorine pulsation chlorinator, which is suitable to be used in water purification in large and medium water works. The chlorinator comprises a chlorinator body and a liquid chlorine feed port, wherein both ends of the body are respectively provided with a water inlet end and a water outlet end, and a reducing pipe, a throat pipe and a divergent pipe which are connected in turn are arranged between the two ends; the liquid chlorine feed port is positioned under the middle part of the throat pipe; the communicated part of the feed port and the throat pipe is a conical valve seat; a normally closed conical valve stem is arranged right above the conical valve seat, and is inserted into the throat pipe from a vertical round hole at the top of the chlorinator body; and the normally closed conical valve stem moves up and down under the control of a pulsation electromagnetic actuator so as to open or close the liquid chlorine feed port. When the normally closed conical valve stem opens the liquid chlorine feed port, liquid chlorine can be fed into the throat pipe from the liquid chlorine feed port so as to turn water flow into a high-concentration chlorine solution; and then, the solution flows out from the divergent pipe and is fed into the water in a clean water tank, thereby completing the chlorine feed working operation. Moreover, a pulsation electromagnetic control mechanism changes electrified rate at any moment by means of an electrified rate automatic adjustment controller, thereby achieving the aim of adjusting chlorine dosage in time.