The　aim　of　this　study　was　to　investigate　the　factors　which　influence　the　denitrification　performance　of　immobilized　denitrifying　bacteria.　Single　variable　control　method　was　used　and　it　was　found　that　the　immobilized　denitrifying　bacteria　particles　had　the　best　denitrification　performance　under　these　conditions:　bacteria　addition　proportion　in　the　immobilized　particles　was　15%　and　with　a　particle　size　of　3-4　mm,　immobilized　particles　adding　amount　was　20%,　and　using　glucose　as　external　carbon　sources　with　carbon-nitrogen　ratios　of　3.0-3.5　and　hydraulic　residence　time　over　6　h　under　the　temperature　of　25　degrees　C-30　degrees　C.　This　study　suggested　that　a　better　denitrification　effect　could　be　achieved　by　extending　the　hydraulic　retention　time　when　other　environmental　factors　are　difficult　to　control.　The　information　obtained　in　this　study　may　help　to　put　the　microbial　immobilized　technology　a　step　forward　in　wastewater　treatment　application.