Hardness removal method and device for high-hardness water

The invention discloses a hardness removal method for high-hardness water. The method comprises the following steps: firstly, mixing high-hardness water with low-hardness underground water which is circulated and refluxed, performing dilution to rapidly reduce the hardness, and feeding the water into a crystallization zone in a guide cylinder; and enabling the underground water in the crystallization zone to flow upwards, mixing the underground water with a precipitant from a center through hole dosing tube in the crystallization zone step by step along the process, keeping a crystallization reaction system at a low ion concentration product level, and gradually reducing the ion concentration product along the process. Under a low ion concentration product condition, homogeneous-phase crystallization in the reaction system can be effectively inhibited, calcium and magnesium ions and precipitant ions are subjected to heterogeneous surface crystallization on the surface of a crystal seedin a crystal constructio