The methods of COD30 and respiratory curve were adopted to evaluate the biodegradability of hyperbranched surfactant which was used as the substrate of microorganism. The main results obtained by the method of respiratory curves were as follows. When the concentration of substrate was 0~250mg/L, the respiratory curves of the substrate were above the curve of endogenous, which showed that the substrate was easy to utilize by microorganism. The main results obtained by the method of COD30 were as follows: when sludge concentration was 1000mg/L and pH was 7, the biodegradation rate of 200mg/L hyperbranched surfactant was 97.8%. The main results obtained by the method of respiratory curves were as follows: When the concentration of substrate was 200 mg/L, the utilization of the substrate by microorganism was the most, respectively. Moreover, the effect of pH, inoculation amount and salinity on the biodegradability of the substrate was obvious. Through experiments, the optimum conditions for the substrate to be degraded could be listed as follows: pH was 8.5, salinity was 0.3% and the range of inoculation amount was 3000mg/L.