The invention discloses rotary hoisting equipment for a stiffening beam of a suspension bridge and an erecting method of the stiffening beam. The rotary hoisting equipment comprises rotary slings, balance beams and a hoisting mechanism, wherein the rotary slings are used for hoisting stiffening beam segments and enabling the hoisted stiffening beam segments to horizontally rotate; the balance beams are positioned right above the rotary slings; the hoisting mechanism is used for hoisting the rotary slings through the balance beams and can move forwards and backwards in the direction longitudinal to the bridge; the stiffening beam segments are hoisted on the rotary slings, the rotary slings are hoisted on the balance beams, and the balance beams are hoisted on the hoisting mechanism and are positioned under the hoisting mechanism; the hoisting mechanism is mounted on cable bent towers of the constructed suspension bridge. The erecting method of the stiffening beam comprises the following steps of: I, erecting a rear-side beam body or a front-side beam body; II, mounting a hoisting balance mechanism; III, erecting a middle beam body; and IV, erecting the front-side beam body or the rear-side beam body. According to the rotary hoisting equipment for the stiffening beam of the suspension bridge and the erecting method of the stiffening beam, disclosed by the invention, the design is reasonable, the realization is convenient, the use effects are good, the construction difficulty is low, and the hoisting and erecting process of the stiffening beam of the suspension bridge can be simply and rapidly completed.