A control structure for a window covering includes a base, a revolving wheel having an axial post, a restriction means including a bushing fitting around the axial post, a transmission member provided on a side of the bushing, and at least one pawl connected to the axial post. The revolving wheel is connected to the base. The restriction means has at least one cutting groove. The transmission member has at least one abutting portion on an inner wall thereof. The pawl is pivotable within a width of the cutting groove. When the revolving wheel is rotated forward, an end of the pawl passes through the cutting groove to mesh with the abutting portion. When the revolving wheel is rotated backward, the pawl disengages from the abutting portion, and the transmission member is rotatable relative to the revolving wheel. Whereby, it could prevent generating noise while operating the window covering.