Curved Arm Manual window opener of a top window opener, a middle window opener, a bottom window operator and a window switch. The bottom window operator is the main drive, and the top and middle window openers are reduction gears, and they are connected through conduit. When opening multiple rows of steel windows, the top window opener is mainly used for opening and closing the highest row of windows, and the middle window opener for opening and closing the middle row of windows. Conduit and switch are fitted to the output shaft of top and middle window openers and the switch is linked to window sashes. When the handle of the operator is turned, top and middle window openers are driven to open or close the window. There is an indicator installed on the output shaft of manual window opener to show the opening and closing angle of the window sash.