This work aimed at decolorizing PET depolymerization waste liquid (DWL) by electrochemical method. PET fabrics were glycolsized by utilizing excess EG and the glycolsis product was purified through repeated crystallization to get BHET crystal. The waste liquid of the depolymerization process was electrochemical decolored by utilizing chitosan/Fe3〇4 nanoparticles as the dispersed electrodes under a 15 V DC voltage. The absorption at 338, 531 and 635 nm which were due to the dyes in DWL decreased with the electrolysis time，while the absorption of EG (322nm) changed slightly. The removal ratio of dyes was described with A/A〇 and achieved to 78.94 %. PET fabrics were depolymerized by using the decolorized DWL and mixture of decolorized DWL with EG (1:1 v / v). The maximum yield of BHET was 58% and 72.3%, respectively.