Abstract: In order to solve the problem that Anammox（ANAMMOX） is difficult to start up quickly, a fixed bed reactor was used to complete the initial start-up of anammox（ANAMMOX） with activated sludge from municipal wastewater treatment plant as inoculated sludge. In the experiment, the temperature of the reactor was controlled at 30℃, pH value was 6.7～8.3, and the dissolved oxygen in artificial wastewater was reduced by nitrogen aeration,The results showed that the non-woven filter cloth and suspended particle biological filler could make AAOB adhere and increase the reaction contact area; when the influent water was 6.18 l/d and HRT was 2.47 d, the highest removal rates of NH₄⁺-N and NO₂^--N were 49.12% and 49. 60% respectively, and the average removal rates were 22. 29% and 14.47% respectively. By comparing the concentrations of NO₂^--N and NH₄⁺-N in the inlet and outlet water and combining with the fish imaging results, it is known that there were a small amount of good nitrogen in the reactor, which proved that the start-up of the reactor had achieved certain results, but the load of anammox system was still relatively low, and the removal rate of ammonia nitrogen was not high, so the start-up of anammox reactor needed to continue.