Anaerobic treatment coupled with micro-electrolysis (ATCM) was applied in treatment of anthraquinone dye wastewater. ATCM performed better in the aspect of the removal efficiencies of chemical oxygen demand (COD) and decolorization than single anaerobic treatment (SAT) did. It was observed that the function of iron was inhibited severely with the reason of mostly coverage of sludge as the experiment was carried out gradually. In order to eliminate the impact of the coverage, electrochemical improvement (external electric field) was studied in the paper. According to the results, the color and COD removal efficiencies were 11% and 32% respectively in SAT, while 65% and 56% respectively in ATCM, and finally 90% and 73% respectively in ATCM improved by external electric field. The removal efficiencies dropped as the Na2SO4 concentration was increased and the pH value reached the maximum value of 9. In the system of ATCM, anaerobic sludge bed contributed more to decolorization than iron bed did, while iron bed played a more important role in ATCM improved by external electric field (ATCM-E). (C) 2012 Elsevier B.V. All rights reserved.