An improvement of roller blinds controller is provided, it mainly comprises a cylindrical rod passing through a side cover and fixing therewith; a bead chain sprocket and a number of torsion springs fitted on the cylindrical rod, and an outer sleeve cover fitted on the outside, wherein: the cylindrical rod has a ridge portion protruded from the circumferential surface thereof, while the side cover has a has a central aperture with a annular edge portion, the cylindrical rod can be fixed with the side cover by the snap-fitting of the annular edge portion between the flange portion and the ridge portion.