The present invention relates to iopromide preparation methods, and provides three new iopromide preparation methods, wherein the method 1 comprises that a compound represented by a formula II is adopted as a starting raw material and reacts with allylamine to obtain a compound represented by a formula III, the compound represented by the formula III reacts with N-methyl allylamine to obtain a compound represented by a formula IV, the compound represented by the formula IV reacts with methoxyacetyl chloride to obtain a compound represented by a formula V, and the compound represented by the formula V is oxidized to obtain the iopromide represented by a formula I, the method 2 comprises that the compound represented by the formula II is adopted as a starting raw material and reacts with allylamine to obtain the compound represented by the formula III, the compound represented by the formula III reacts with methoxyacetyl chloride to obtain a compound represented by a formula IV-1, the compound represented by the formula IV-1 reacts with N-methyl allylamine to obtain the compound represented by the formula V, and the compound represented by the formula V is oxidized to obtain the iopromide represented by the formula I, the method 3 comprises that the compound represented by the formula II is adopted as a starting raw material and reacts with allylamine to obtain the compound represented by the formula III, the compound represented by the formula III reacts with methoxyacetyl chloride to obtain the compound represented by the formula IV-1, the compound represented by the formula IV-1 reacts with 3-methylamino-1,2-propanediol to obtain a compound represented by a formula V-1, and the compound represented by the formula V-1 is oxidized to obtain the iopromide represented by the formula I, and the method 4 comprises that the compound represented by the formula II is adopted as a starting raw material and reacts with methoxyacetyl chloride obtain a compound represented by a formula III-1, the compound represented by the formula III-1 reacts with allylamine to obtain the compound represented by the formula IV-1, the compound represented by the formula IV-1 reacts with N-methyl allylamine to obtain the compound represented by the formula V, and the compound represented by the formula V is oxidized to obtain the iopromide represented by the formula I.