Due to the low efficiency of traditional azo dye treatment process, in this study a novel up-flow biocatalyzed electrolysis reactor was used for azo dye alizarin yellow R (AYR) decolorization. The reactor operated in an up-flow, continuous flow mode, and the results showed that the decolorization efficiency was 82.1％ and the decolorization rate was 1.74 mol·m-3·d-1 at HRT of 4 h. The chrominance of the effluent was as low as 80. AYR was mainly discolored via electrochemical reaction in the cathode zone of UBER. The bio-anode also made some contribution to the decolorization. Two stable products p-phenylenediamine and 5-aminosalicylic acid were produced finally without accumulation of nitro intermediates.