The invention provides a carbon fiber wastewater treatment method and a treatment device. The treatment method includes steps: feeding carbon fiber wastewater into a distillation tower, and separatingout dimethyl sulfoxide and acrylonitrile from the carbon fiber wastewater; feeding the separated acrylonitrile into a polymerization reactor to realize polymerization reaction; feeding the separateddimethyl sulfoxide into a rectifying tower to realize purification. After the acrylonitrile and dimethyl sulfoxide in the wastewater are subjected to distillation separation treatment, the separated acrylonitrile is subjected to self-polymerization while the dimethyl sulfoxide is subjected to rectifying concentration, so that the removal rate of impurities in the wastewater is high, and low environmental pollution is realized.