The invention discloses a concrete beam closure structure of a hybrid beam rigid frame bridge under a strong surge condition. The concrete beam closure structure comprises a pair of reinforced concrete combination sections which are symmetrically arranged on two concrete beams to be closed, wherein the joints of the pair of reinforced concrete combination sections form a closure opening, and the lengths of a top plate, a web plate and a bottom plate of the joints of the reinforced concrete combination sections are sequentially increased along a longitudinal bridge direction, so that the sections of the joints along the longitudinal bridge direction are Z-shaped; a large-section steel box girder, wherein the relative positions of a top plate, a web plate and a bottom plate of the large-section steel box girder are matched with the pair of steel-concrete combined sections, and the lengths of the top plate, the web plate and the bottom plate of the large-section steel box girder along thelongitudinal bridge direction are sequentially decreased progressively, so that the sections at the two sides of the large-section steel box girder along the longitudinal bridge direction are Z-shaped. The invention further discloses a method for lowering, staggering and closing the large-section steel box girder of the hybrid beam rigid frame bridge under the strong surge condition. According tothe method, under the strong surge condition, the rapid and accurate closure of the large-section steel box girder can be achieved, and the width error of the weld joint of the closure is smaller than 1 cm.