Abstract: In this study, IC anaerobic technology was used to evaluate the start-up and operation of the pilot-scale reactor with the methane production potential of activated sludge as an indicator. The influence of the water quality parameters and running conditions on the treatment performance during the load increasing process was investigated in detail. The results showed that the IC anaerobic reactor has a good capacity of COD_Cr reduction rate of 50%-60% when the influent COD_Cr was 2000 mg/L and the biogas output was maintained at 1.1 m³/d. The removal rate of sulfate could reach 92%-98% and the digestive liquid VFA/ALK was less than 0.3 when the pH was controlled between 7.5 and 8 and the C/S (C/S ratio, COD/SO₄^2-) was more than 2.5. The tolerance limit of the IC system to sulfide was 220 mg/L. The volumetric load during the whole process was less than 1.5 kg COD_Cr/m³·d, and the rising flow rate was less than 2 m/h. These results show that the IC anaerobic reactor have a strong tolerance to the tannery wastewater after start-up, and have a good application prospect under proper operating conditions.