This　paper　selects　the　dissolved　oxygen　(DO)　concentration　and　the　effluent　ammonia　concentration　(NH4+-N)　as　control　factors,　exploring　the　feasibility　of　nitrification　and　the　value　of　DO/NH4+-N　(R-value)　in　biofilm　process　under　the　different　temperature　and　organic　carbon　source　dosage　(COD/NH4+-N).　At　15,　20,　25,　the　DO/NH4+-N　value　of　partial　nitrification　was　about　0.08,　0.17,　0.25,　respectively.　It　shows　that　ratio　control　can　realize　partial　nitrification,　and　the　reduction　of　R　can　make　up　for　the　adverse　effect　of　temperature　reduction.When　the　concentration　of　DO　was　3.5mg/L　and　the　ammonia　concentration　was　14mg/L,　the　partial　nitrification　was　achieved,　while　the　concentration　of　DO　and　ammonia　respectively　was　1.8mg/L,　3mg/L,　and　the　partial　nitrification　was　destroyed,　which　indicated　that　the　realization　of　partial　nitrification　in　biofilm　reactor　was　decided　by　DO/NH4+-N,　not　just　DO.　The　organic　carbon　content　were　0,　60mg/L　respectively,　R-value　of　partial　nitrification　increasing　from　0.25　to　0.38,　but　the　partial　nitrification　damaging　in　R=0.6,　which　illustrated　that　the　more　organic　carbon　source　were　added,　the　regulation　scope　of　R　is　broader,　facilitating　the　realization　of　partial　nitrification,　but　the　R　amplification　is　limited.　©　2017,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.