The present invention discloses a liquid-state heavy metal oxygen concentration control solid-liquid exchange reaction apparatus under the flowing working condition, wherein the oxygen concentration in the whole liquid-state heavy metal system is adjusted by controlling the temperature and the flow rate of the liquid-state heavy metal flowing through a reaction container. With the apparatus of the present invention, the problems of the reaction container temperature control, no damage of the mass exchanger on the whole reaction container and the like are cleverly solved. The apparatus comprises a mass exchanger, an oxygen measurement meter, a built-in heating rod, a built-in thermocouple, an air cooling device, a filtration screen type filter, a liquid-state metal valve, a liquid-state metal flow meter, and a reaction container. According to the present invention, the temperature of the liquid-state heavy metal is stable and controllable; the electronically controlled liquid-state metal valve and the liquid-state metal flow meter are adopted to precisely control the flow rate of the liquid-state metal in the reaction container; the filtration screen type filter is arranged, the impurity in the liquid-state heavy metal can be filtered out, and the influence of entering of the impurity into the mass exchanger and adsorbing on the surface of oxygen source particles on the oxygen source particle oxygen exchange efficiency can be prevented; and the flange type or ferrule type connection is adopted so as to provide characteristics of easy removal, easy replacement and easy maintenance.