Abstract: The present disclosure relates to a spring winder having a winder base, pulleys disposed at one end of the winder base, at least one constant force spring disposed on the winder base, each constant force spring having an extension end, and a guard plate is disposed at one side of the extension end of each constant force spring. A curtain using the spring winder is also described having an upper beam; a lower beam; and a curtain disposed between the upper beam and the lower beam, the upper beam having a spring winder disposed therein; a fixed plug head disposed at one end of the upper beam, a fixed pulley plug head disposed at the other end of the upper beam, each constant force spring of the spring winder being connected to the fixed plug head, a cord winding around the pulleys, the cord being connected to the pulleys at the fixed pulley plug head after being connected to the curtain.