The invention discloses a method for treating pickling waste water from stainless steel cold-rolling. The method comprises: performing ultrafiltration and reverse osmosis treatment of the pickling waste water from stainless steel cold-rolling; and performing multiple-effect evaporation of the waste water containing nitrate after ultrafiltration and reverse osmosis treatment to enable nitrate to be crystallized from the waste water. Accordingly, the invention also discloses a device for treating the pickling waste water from stainless steel cold-rolling, wherein the device comprises: an ultrafiltration device for performing ultrafiltration treatment of the pickling waste water from stainless steel cold-rolling; a reverse osmosis device connected to the ultrafiltration device and used for performing reverse osmosis treatment of the pickling waste water from stainless steel cold-rolling; a pre-heater, an input terminal of which is connected to an output terminal of the ultrafiltration device; a multi-effect evaporator component including a plurality of evaporators, a plurality of separators corresponding to the plurality of evaporators, and a steam inputting terminal, wherein the input terminal of the multi-effect evaporator component is connected to an output terminal of the pre-heater, the output terminal of the multi-effect evaporator component outputs a thick nitrate crystal liquid; and a centrifugal machine connected to the output terminal of the multi-effect evaporator component and used for separating nitrate crystal from the thick nitrate crystal liquid.