To　ensure　the　water　quality　in　long　distance　pipeline　transportation,　the　influence　of　dissolved　oxygen　(DO)　on　water　quality　and　recovery　process　after　aeration　oxygenation　were　studied　in　a　pipeline　reactor　that　could　simulate　this　long　distance　pipeline　transportation.　The　results　showed　that　the　decrease　of　DO　could　reduce　the　removal　of　ammonia　nitrogen　(NH4+-N),　and　the　lower　DO　concentration　was　the　more　unfavorable　removal　of　NH4+-N,　the　slower　recovery　after　aeration　oxygenation　was.　The　removal　rate　of　NH4+-N　declined　from　90%　to　21%　and　85%　after　reactor　run　95　h　at　DO=0.5　mg　·　L-1　and　1.5　mg　·　L-1,　and　the　recovery　after　aeration　oxygenation　took　54　h　and　3　h　respectively.　The　accumulation　of　nitrite　nitrogen　(NO2--N)　increased　significantly　as　DO　reduced,　and　the　lower　DO　concentration　was　the　more　favorable　accumulation　of　NO2--N,　the　slower　recovery　after　aeration　oxygenation　was.　At　DO=0.5　mg　·　L-1　nitrite　nitrogen　increased　from　0.02　mg　·　L-1　to　0.354　mg　·　L-1　after　reactor　run　95　h,　and　the　recovery　after　aeration　oxygenation　took　54　h.　While　the　maximum　value　of　nitrite　nitrogen　was　0.112　mg　·　L-1　after　reactor　run　32　h　at　DO=1.5　mg　·　L-1,　and　the　recovery　after　aeration　oxygenation　took　only　4　h.　The　decrease　of　DO　concentration　could　lead　to　rise　of　UV254.　UV254　increased　by　70.8%　and　20.8%　after　reactor　run　2　h　at　DO=0.5　mg　·　L-1　and　1.5　mg　·　L-1,　respectively,　and　both　recovery　took　32　h,　and　then　it　was　relatively　stable　after　aeration　oxygenation.　Therefore,　DO　is　of　important　impact　on　water　quality　in　long　distance　pipeline　transportation,　and　could　used　for　the　regulation　of　water　quality.　©　All　Rights　Reserved.