Embedded　immobilized　bacteria　particles　are　used　to　treat　the　secondary　effluent　from　the　wastewater　treatment　plant　of　Beijing.　The　effects　of　hydraulic　retention　time,　TN　loading　rate　and　the　particle　filling　ratio　on　the　culture　process　of　embedded　immobilized　bacteria　and　nitrogen　removal　efficiency　were　investigated　here.　The　results　showed　that　a　stable　and　high　nitrogen　removal　efficiency　was　achieved　in　the　condition　of　temperature　25°C,　pH　7.2,　hydraulic　retention　time　70　min　and　filling　ratio　30%　after　adding　the　carbon　sources　for　one　week.　An　excellent　resilience　to　the　load　shock　was　observed　in　our　operating　system.　The　average　TN　removal　efficiency　reached　86.6%,　when　the　TN　loading　rate　varied　from　0.5　kg·m-3·d-1　to　2.0　kg·m-3·d-1.　The　TN　can　be　removed　by　70%　with　the　TN　loading　rate　2.5　kg·m-3·d-1.　The　effluent　concentration　of　nitrate　nitrogen　and　total　nitrogen　were　less　than　1　mg·L-1and　5　mg·L-1　respectively　at　HRT　20　min.　A　TN　removal　efficiency　higher　than　80%　was　achieved　when　the　filling　ratio　changed　from　30%　to　20%.　However,　the　TN　removal　efficiency　decreased　with　the　filling　ratio　when　the　filling　ratio　was　less　than　20%.　The　optimized　filling　ratio　of　embedded　immobilized　bacteria　was　20%　in　the　experiment.