In order to evaluate the feasibility of the fast startup of Anammox process, a lab-scale Anammox baffled biofilm reactor was carried out in this study. The experimental conditions were maintained at temperature (30±2)℃, DO 0.2-0.5 mg/L, pH 7.6-8.0, average ammonia nitrogen load at 0.12 kg/(m³·d) and nitrite nitrogen load at 0.18 kg/(m³·d), respectively. By taking continuous low strength influent, the start-up process was successfully achieved within 83 days. After the fast startup, the average concentration of effluent NH₄⁺ -N, NO₂^--N and TN were 1.5, 1 and 10 mg/L, respectively. Meanwhile, the average removal efficiencies of NH₄⁺ -N, NO₂^--N and TN reached 95%, 95% and 80%, respectively. The effluent could stably meet the first grade A standards of Urban Sewage Disposal Plant Contamination Integrated Discharge Standard of China (GB 18918-2002). Under the stable phase, the removal rate of NO₂^--N in each compartment along the reactor gradually decreased, and the remove of NH₄⁺ -N presented in some delay.