The invention relates to a method for treating acidic wastewater of an acrylic acid device. According to the method, a coupling technology is adopted for treating the acidic wastewater; according to the coupling technology, an oxidant is used for oxidizing and removing formaldehyde, acetaldehyde and acraldehyde out of the acidic wastewater; an alkali is used for neutralizing acetic acid and acrylic acid in oxidizing liquid; neutralizing liquid is separated by a membrane to remove water; and finally reduced-pressure concentrating, crystallizing and drying are carried out to prepare acetate. The formaldehyde removing rate of the oxidizing liquid in the method is more than 99.5%; after the neutralizing liquid is subjected to RO (Reverse Osmosis) membrane separation, transmitting liquid reaches national environment protection emission Standard II; the yield of sodium acetate trihydrate is more than 7.7% on the basis of the raw material acidic wastewater; and the sodium acetate trihydrate product can be used as a raw material of a snow-melting agent.