The invention discloses an internal formation process for a high-capacity gel battery, which comprises the following steps in turn: assembling a battery, pouring dilute sulphuric acid with the density of 1.240g/cm3 into the battery, wherein the dilute sulphuric acid is prepared from concentrated sulfuric acid and water, and 1 to 1.5 weight percent of sodium sulfate, 0.1 to 0.5 weight percent of potassium sulfate and 0.2 to 0.6 weight percent of stannous sulfate are added into the dilute sulphuric acid; charging and discharging I; pouring gel into the battery, wherein gel electrolyte prepared by mixing 3 to 5 weight percent of silica, 0.1 to 0.5 weight percent of polyethyleneglycol, 0.5 to 1.2 weight percent of sodium sulfate and the balance of water is quantitatively poured into the battery under vacuum; charging and discharging II; grouping the battery; and packing the battery. The internal formation process for the high-capacity gel battery has the advantages that: the sulphuric acid after charge and discharge and the aqueous solution of silica are mixed naturally to form the gel having a uniform and stable structure; the actual sulphuric acid amount in the battery can be controlled precisely and effectively; the grouping precision of the storage battery can be controlled; the consistency of the storage battery is improved; and the service life of the storage battery is prolonged.