The invention relates to a load optimization method of an ion membrane electrolyzer, and belongs to the technical field of electrolyzers. The load optimization method is characterized in that the adjusting step is as follows: according to the average load operation situation of each electrolyzer, electrolyzers are divided into high, middle-high, middle, middle-low and low fives grade, under the premise of ensuring the same total current, according to the divided fives grade of the electrolyzers in step 2), partial current of each electrolyzer is adjusted, the partial current of a high grade electrolyzer is reduced to 10% to 30%, the partial current of a middle-high electrolyzer is reduced to 5% to 10%, the partial current of a middle electrolyzer is not changed, the partial current of a middle-low electrolyzer is increased by 5%-10%, and the partial current of a low electrolyzer is increased by 10% to 20%. Through the load optimization method for load optimization of the electrolyzers, low DC power consumption and low acid consumption of the electrolytic device can be achieved, and the operating life of an ionic membrane can be prolonged.