The invention discloses a method for treating 
pickling wastewater in iron and steel industry. The method comprises the following steps: a) introducing 
pickling wastewater into a regulating tank, a 
chromium reduction tank and a heavy 
metal catcher; b) separating heavy 
metal precipitate produced in reaction from clear liquor through an ultramicro separating 
machine, carrying out primary 
fluoride removal on the clear liquor in a 
fluoride removal filter; c) feeding the 
mixed solution subjected to primary 
fluoride removal into a primary precipitating tank for separating non-
ferrous precipitate from water, then carrying out secondary fluoride removal on the clear liquor in a fluoride reaction tank; and d) feeding the 
mixed solution subjected to secondary fluoride removal into a secondary precipitating tank for separating non-
ferrous precipitate from water, and emitting the separated clear liquor into a clear water tank for storage. The method has high 
metal particle separation efficiency, the ultramicro separation 
machine has 
concentration effect, so no concentration tank is required for separating the precipitate from the clear liquor to save space and the labor force, the indexes of iron, 
chromium, 
nickel, fluoride and the like in the clear liquor emitted from the secondary precipitating tank can all meet the national-level standard requirement.