An integrated flattening, cutting, and collecting assembly includes a frame, a conveyor seat, and a processing rack. The processing rack is provided with a flattening cylinder and cutting cylinders, a flattening block cooperating with a steel sheet being conveyed by the conveyor seat, a cutting lift seat disposed beneath the cutting cylinders, the cutting lift seat being provided with a cutter and cutting pressing blocks, and wherein the distance between the two cutting pressing blocks is smaller than the length of the flattening block. In addition, the lower end of the cutter is disposed beneath the lower ends of the cutting pressing blocks, and this distance is the same as the thickness of the steel sheet being conveyed. The cutting pressing blocks can press and hold the steel sheet during cutting, while not affecting the cutting of the cutter, whereby the accuracy of the steel sheet cutting is greatly improved.