Abstract: The point-stack model has obvious advantages over computational fluid dynamics（CFD） when solving long-term transient oxygen concentration in complex geometric structures,and could be better transplanted into the model prediction system. This study simulates the influencing factors of mass exchanger’s（MX） performance in the CRAFT loop by combining with the PbO dissolution model and liquid lead bismuth eutectic（LBE） corrosion model, using point-stack model and programming in assembly language. The effects of the mass flow rate of the primary loop, the mass flow rate of bypass of oxygen supplying to the primary loop,temperature in the MX and loading quality of Pb O were studied. The results showed that the mass flow rate of the primary loop, the loading amount of Pb O were positively correlated with the time of establishing equilibrium and the value of equilibrium oxygen, the mass flow rate of bypass of oxygen supplying and the primary loop is inversely related to it. However, the temperature in the MX is positively correlated with the equilibrium oxygen concentration.Therefore, the performance of oxygen control bypass can be improved by increasing the flow rate between the oxygen control bypass and the primary loop, the operating temperature and lead oxide loading in the MX should match the bench.