Water-saving toilet water tank with stepless flushing amount adjusting function

The invention discloses a water-saving toilet water tank with a stepless flushing amount adjusting function. A water inlet valve and a pontoon are arranged in the tank body of the water tank; a flushing mechanism and a flushing amount adjusting mechanism are further arranged in the tank body of the water tank; the flushing mechanism comprises a drain valve, a pull rod, a lever, a connecting pieceand a flushing button; the flushing amount adjusting mechanism comprises a flushing amount adjusting knob, an outer sleeve and an inner sleeve; the sleeve wall of the outer sleeve is provided with a first gap; the sleeve wall of the inner sleeve is provided with a second gap; the second gap is an incision which inclines from top to bottom along the sleeve wall of the inner sleeve; and the flushing amount is adjusted by adjusting a superposed region between the first gap and the second gap. The water-saving toilet water tank has the advantages of realization of stepless adjustment of the flushing amount of a toilet, ea