Flattening method and rolling method of sheet strip steel

The invention discloses a flattening method and a rolling method of sheet strip steel. The flattening method for the sheet strip steel comprises the steps that, S1, replacing a flattening working roller with a first CVC type working roller; S2, setting operation parameters; S3, flattening the sheet strip steel for the first time; S4, judging whether the double-side crimp defect is improved to be within a required straightness range or not, if so, executing the step S5, and if not, executing the step S3; S5, judging whether a middle crimp defect exists or not, if yes, executing the step S6, and if not, executing the step S8; S6, replacing with a second CVC type working roller, and flattening the thin plate strip steel for the second time; S7, judging whether the middle crimp defect is improved to be within the required straightness range or not, if yes, executing the step S8, and if not, executing the step S6; and S8, ending. According to the flattening method of the sheet strip steel, the double-side crimp de