Wastewater evaporator for chemical organic wastewater with high salt and high concentration, based on the principle of evaporation, concentration and crystallization. Multi-effect decompression evaporation and crystallization of organic wastewater, the salt in the concentrate is separated and recovered through the salt collector, and the concentrate is dried and recycled or incinerated, and the evaporated condensate is generally treated through subsequent biochemical treatment, which can realize the standard of wastewater discharge. The hourly evaporation capacity of the evaporator is divided into 1-30 tons from small to large, in which the concentration ratio of the four-effect evaporator reaches 10-15%. It can be delivered as a turnkey project.