The invention relates to a liquid soap feeding device, in particular to a self-suction liquid soap feeding device which utilizes the water pressure to suck liquid soap. The device is provided with a liquid suctionor and a liquid suction controller thereof which use the water pressure as power to change the volume of the liquid suction cavity and achieve the aim of sucking or squeezing out the liquid soap. Therefore, the parts such as the motor and the gear pump are not needed; and the squeezing amount of the liquid soap is only related to the variation quantity of the volume of the liquid suction cavity, thus the squeezing amount of the liquid soap is stable and the squeezing amount can be conveniently changed by adjusting the volume of the liquid suction cavity.