In this paper, potato starch wastewater (PSW) was adopted as anaerobic co-substrate added in influent of coal gasification wastewater (CGW). The control anaerobic biofilters (AF) and supplemented AF were investigated in our research. Without co-digestion, both of the COD and total phenol removal rates were only 30%, respectively. However, adding PSW (COD = 1000 mg/L) as co-substrate meanwhile increasing concentration of CGW in influent step by step from phase 1 to phase 3. In phase 1 and 2, the effluent COD and total phenol reached 1000 mg/L and 50 mg/L, respectively. Further increasing COD of PSW to 1500 mg/L in phase 4, the removal rates of COD and total phenol almost reached 50%, respectively. The methane production rate was increased to 260 mLCH₄/gCOD/d. In order to further improve the treatment efficiency in co-digestion, the two-stage AFs were adopted in our next study, the result indicated that with adding PSW (COD = 1500 mg/L) in the first stage AF (R1) and extending the HRT of R1 to 48 h, both of the total removal rates of COD and total phenol almost reached 75%, respectively, meanwhile methane production rate of the second AF (R2) rising to 300 mLCH₄/gCOD/d in phase 4.