The invention discloses a device for processing flat steel. The device comprises a supporting base, a power system and a clamping plate, wherein the clamping plate is connected with the supporting base; the supporting base comprises a supporting plate and a supporting pillar; a through hole is formed on the middle part of the supporting plate; two slide slots are formed on the supporting plate; the clamping plate comprises a base plate and two clamping bases; the base plate is fixedly connected with the clamping bases; U-shaped slots are formed on the clamping bases; slide blocks corresponding to the slide slots are arranged at the bottom of the clamping bases; openings of the U-shaped slots on the two clamping bases are opposite to each other; two sleeves are arranged on the supporting base; thread holes are arranged as inner holes of the sleeves; a screw rod is arranged in the thread holes; a baffle is arranged on an end part of the screw rod close to the clamping plate; the power system comprises a motor, a rotating shaft and a rotating rod; idler wheels are arranged at the two ends of the rotating rod; the rotating shaft is connected with the motor through a flange; a thrust bearing is arranged at the through hole on the supporting plate; the rotating shaft passes through the through hole on the supporting plate. The device for processing flat steel overcomes the defect of low working efficiency during the process of bending the flat steel in the processing of flat steel spring in the prior art.