A venetian blind operating device comprises a wand having a center hole and a slide slot. The slide slot runs through the wand in an axial direction and intersects the center hole. In addition, the operating device comprises a blind cord locking assembly locked in the center hole of the wand and coupled to a blind cord of a venetian blind. Further, the operating device comprises a control key surroundingly provided at a periphery of the wand, and a press key provided on the control key for disengaging the blind cord locking assembly from a locked state. The blind cord is hidden by being contained in the center hole of the wand. The press key, the control key and the blind cord locking assembly are cooperated to withdraw or draw the venetian blind.