The invention provides an auxiliary roller structure with the roller-bending forming angle capable of being adjusted with a large range and an adjusting method. The auxiliary roller structure comprises a supporting straddle plate (1). A left auxiliary roller unit (2) and a right auxiliary roller unit (3) are symmetrically mounted on the left side and the right side of the supporting straddle plate (1). The left auxiliary roller unit (2) comprises an upper supporting plate (4), a lower supporting plate (5), a connecting shaft (6), an auxiliary roller unit body (7), a transverse displacement adjusting unit (8) and an upper-lower supporting plate angle adjusting unit (9). The auxiliary roller structure has the advantages that (1) the size of a specimen does not need to be considered, a transverse displacement bolt is rotated, a side roller assembling body can move on the side roller supporting straddle plate, accordingly, abrasion, caused by dismounting and mounting for multiple times, of a rack is avoided, wasting of working hours is reduced, and the experiment cost is reduced; and (2) the device is simple in structure and easy to operate, and the working hours are saved.