The present invention relates to a reel-driving device for a rolling blind, which is characterized in that the reel-driving device consists of a guyrope turntable box, a guyrope turntable, a curtain reel and an unidirectional on-off device which consists of a rotation shaft and an on-off slide rotation head, wherein the rotation shaft is arranged on the axial line of a curtain reel and drives the curtain reel to rotate, and the on-off slide rotation head is arranged on the same axial line as the rotation shaft. The end face which is connected with the rotation shaft and the on-off slide rotation head is provided with unidirectional engaged teeth, a pressure spring is arranged between the rotation shaft and the on-off slide rotation head, the external surface of the other end of the on-off slide rotation head is provided with a chute, a slide block is arranged in a sleeve which is arranged at the side of the guyrope turntable corresponding to the chute, and a spring ring is connected between an axle hole and the external surface of the on-off side rotation head. Compared with the prior art, the reel-driving device has the advantages that the guyrope turntable can accommodate more ropes, and a guyrope-driving mechanism cannot affect the curtain reel when the curtain reel turns, and the structure is simple.