The invention discloses an apparatus for removing temporary hardness in water during tower type water fall. The apparatus is used for solving the problems that water having high temporary hardness generates precipitates, forms water scales and the like after being boiled. The apparatus is divided into three stages according to the difference of water purifying units, wherein each pipeline is formed by connecting with flanges; the apparatus is divided into an acid adding and mixing unit, a water fall carbon-removing unit and a water collecting unit. A chemical agent added in the acid adding and mixing unit is hydrochloric acid, the mixing is for a purpose of realizing sufficient mixing reaction of raw water and the chemical agent, and the acid adding and mixing unit has an effect of removing HCO<3-> from water; the water fall carbon-removing unit aims at removing CO2, which is dissolved in water, generated in the reaction of the acid adding and mixing unit; the water collecting unit has an effect of collecting treated water and adding a chemical agent (sodium hydroxide) to adjust pH value to a normal level. The apparatus is compact in connection of various functional units, simple in principle and convenient to mount and dismount, and has high scale removal rate against raw water having high temporary hardness, and the scale of the apparatus can be adjusted according to different requirements.