A flexible pre-pressing device for a corrugator roll comprises a base (2) and a set of flexible pre-pressing device bodies. Each flexible pre-pressing device body is composed of a support (3), a pair of guide pins (4), an airbag (5) and two pairs of pre-pressing rolling wheels (6). The top face of the base (2) is inclined, a plurality of pairs of pin passing holes and a rolling wheel mounting plate are arranged on the base (2), a pair of pin passing holes is formed in each support (3), and each pair of guide pins (4) penetrates through the pin passing holes in the corresponding support (3) and one pair of pin passing holes in the base (2). The structure is simple, mounting and adjusting are convenient, deformation of all axial segments of the corrugator roll in the direction perpendicular to the axial direction is changed more flexibly, middle-high-value flexibility of the corrugator roll can be changed, the corrugator roll adapts to different paper product ranges, and therefore the problem that the paper product adaptability is poor due to the deficiency of middle-high design of the corrugator roll is solved.