The invention discloses a softening device and control method of a dish-washing machine and the dish-washing machine. The softening device comprises a water inlet pipeline, a salt water cavity and a resin cavity, wherein the resin cavity communicates with the water inlet pipeline, the salt water cavity communicates with the resin cavity, and a water storage cavity is also included; and the liquidinlet of the water storage cavity communicates with the resin cavity, the liquid outlet of the water storage cavity communicates with the salt water cavity and/or the interior of the dish-washing machine, and a medium which is stored in the water storage cavity is used for absorbing heat in the dish-washing machine or in the surrounding environment for energy storage. Through the softening device,the additional water storage cavity is added, softened water is stored in the water storage cavity with a stable pressure, and when the softened water is introduced into the salt water cavity, salt water can be introduced into the resin cavity for resin regeneration, so that required rated salt water is saved, and the effect of resin regeneration is improved; meanwhile, the water storage cavity can also be used for absorbing heat for energy storage, so that resources are saved, and energy consumption is reduced; and moreover, the salt water cavity and the resin cavity are formed in an equallysplit mode, so that installation has more flexible positions, more space is saved, and addition and supplementation of salt are convenient for a user.