The invention belongs to the field of superconducting magnets, and particularly relates to an ReBCO spiral coated conductor sheet-based superconducting magnet and a preparation method. A main body structure of the superconducting magnet is formed by alternately stacking superconducting sheets and insulating sheets, wherein one insulating sheet is arranged between each two superconducting sheets; and the ReBCO spiral coated conductor sheet-based superconducting magnet also comprises a current lead and a fixing device. An ReBCO spiral coated conductor is adopted by each superconducting sheet; the superconducting surface is cut into spiral bands by laser light; and current is uninterruptedly transmitted along the spiral bands through welding the end parts of the spiral bands, the magnet is fixed through an upper flange plate, a lower flange plate and a pull rod, and the superconducting magnets with different sizes are finally nested to strengthen the generated magnetic field. The ReBCO spiral coated conductor sheet-based superconducting magnet has the advantages of high energy density, small loss and small volume, a flux jump can be avoided and the high-end technical demands of high field intensity, high energy density and the like are more easily met.