The invention relates to a contact heating based bending banknote flattening device, and belongs to the technical field of financial automation equipment. The bending banknote flattening device comprises the components such as a flattening roller assembly, a heating device and a banknote conveying track, and is characterized in that the flattening roller assembly comprises a front driving roller, a middle driving roller, a rear driving roller, a front pressing roller and a rear pressing roller which are equal in diameter; the front driving roller, the middle driving roller and the rear driving roller are arranged in a V-shaped manner, and the front driving roller and the rear driving roller are respectively installed with the front pressing roller and the rear pressing roller in a paired manner. According to the invention, a contact heating mode is adopted, a function existing between the radius of each flattening roller and the heating temperature is provided, and the lowest temperature needed for realizing a required flattening effect can be calculated under the condition that the minimum allowed flattening roller radius is known, so that a circumstance that the safety of surrounding plastic parts is affected by an excessively high temperature of the heating device is avoided; and the bending banknote flattening device perform heat transfer through a cylindrical heat transferring belt, thereby being high in heating efficiency, small in heat inertia and easy to control. The bending banknote flattening device adopts a typical transmission mode in structure, thereby being easy to form a systemic and modular design scheme.