The invention provides a method for measuring heavy metal in seawater by using an ion chromatography flow injection chemical luminescence suppression method; the method is based on that the heavy metal elements in seawater have obvious suppression effect on ozone oxidation rhodamine B chemical luminescence system, at the same time the difference of suppression level of the chemical luminescence intensity and the concentration of the heavy metal elements in seawater have linear relation, and a method for using an ion chromatography flow injection chemical luminescence suppression method to measure heavy metal in seawater is established by using the ion chromatography separation flow injection technology; the method used for measuring the heavy metal in seawater has the advantages of on spot, fastness, simplicity and sensitivity.