The invention discloses an offshore oilfield acidification output increase system which is prepared from the following raw materials in percentage by weight: 20-50% of a chelated acid, 3-5% of NH4F, 2-3% of a corrosion inhibitor, 1-3% of a mutual solvent, 1-2% of a clay stabilizer and the balance of water. According to the offshore oilfield acidification output increase system, the chelated acid is adopted to provide H<+>, the chelated acid and NH4F in the system form a chelated soil acid system, after the system is fed into a well and encounters clay minerals and mud, H<+> can be continuouslyprovided from the chelated acid, and at the same time F- in the system can be consumed; since the chelated acid self has a relatively good chelation property for metals, chelation of heavy metals such as iron can be ensured in the application process, and secondary deposition which can do harm to reservoirs can be avoided; on the other hand, the chelated acid has the characteristic of low acidity, and an approximately neutral acid value can be achieved after reactions, so that the collection amount of residual liquids after reactions can be greatly reduced, the operation cost can be greatly reduced, and the benefits can be effectively increased.