The invention discloses a multi-pass curvature decreasing straightening technology. The straightening technology comprises the steps of computing the largest mesh amount required for straightening a steel plate to be straightened through a model according to information of the steel plate to be straightened, determining straightening passes according to the straightening capability of a straightening machine, allocating set amount of inlet roll gaps and outlet roll gaps of all the passes, computing the set amount of outlet side rolls through a springback deformation model, preventing the head and tail of the steel plate from warping, guaranteeing smooth connecting of strengthening of all the passes, and enabling the steel plate to realize multi-pass curvature decreasing straightening. By adopting the straightening technology, the original design straightening range of the straightening machine can be broadened, meanwhile the stress distribution uniformity in the thickness direction of the straightened steel plate is reduced, and the shape quality of the steel plate is improved.