The invention discloses a new water-saving device, it is mainly composed by screw cap, adjusting cap, reinstalling spring and nominal. Said screw cap and adjusting cap's tops all have a flushing port, the flushing port's diameter of the adjusting cap is smaller than that of the screw cap, and the two flushing ports of the screw cap and the adjusting cap form the inhalant canal. The toroidal gaps form the apopore, and the gaps are between the undersurface of said adjusting cap and the internal terrace set in the noumenon. The invention has less elements and the structure is simple. The invention makes use of the pressure formative from fluid acting on the adjusting cap to drive the adjusting cap to move up and down in the noumenon to change the apopore's caliber size, realizing the water yield's stationary and conformity. It can accurately control the rate through adjusting preinstalled spring's preloading.