The invention provides a mechanical rolling straightening device for a T section. The device comprises a roller set, wherein the roller set comprises a roller and a roller ring; the roller set is composed of an upper roller set and a lower roller set; a transverse processing clearance is formed between the upper roller set and the lower roller set; the roller is composed of an upper roller and a lower roller; the roller ring is composed of an upper roller ring and lower roller rings; the upper roller set comprises an upper roller and upper roller rings; the lower roller set comprises a lower roller and a lower roller ring; the upper roller ring and the lower roller ring are correspondingly arranged on the upper roller and the lower roller by sleeving; a plurality of upper roller rings and/ or a plurality of lower roller rings are arranged; longitudinal processing clearances are formed among the plurality of upper roller rings and/ or the plurality of lower roller rings. The invention also provides a correcting method using the abovementioned mechanical rolling straightening device for the T section. According to the device and the method, a T-shaped aluminum alloy stringer can be mechanically rolled and straightened after being quenched and deformed, so that the production efficiency of the T-shaped stringer can be greatly increased, and moreover, the working intensity of operators can be reduced.