The invention provides a method for preparing NaCl industrial salt with desulphurization waste water zero discharge. First, suspensions and colloids in desulphurization waste water are aggregated into large particles and precipitate, then the waste water without suspensions and colloids is evaporated, during the initial period of evaporation, seed crystals are added into the waste water, thus substances easy to scale are precipitated, the precipitated substances easy to scale are discharged, the residual solution system is subjected to condensation, crystallization, dehydration and drying, and NaCl industrial salt with a high purity is obtained. Through a mode of addition of seed crystals, the substances easy to scale in the waste water are precipitated with the seed crystals as crystal nucleuses firstly, then the precipitated substances easy to scale are discharged, the impurity ion content in the waste water system is lowered, the waste water hardness is lowered effectively, scaling on inner surfaces of a waste water processing device can be avoided effectively, and finally production of NaCl industrial salt products with a high purity can be achieved.