The　combination　of　chlorine　dioxide　(ClO2)　and　chlorine　(NaOCl)　or　monochloramine　(NH2Cl)　was　used　to　degrade　the　formation　of　ClO2-,　when　ClO2　was　used　as　an　effective　oxidant　which　could　form　undesirable　oxidation　by-products,　i.e.　ClO2-.　In　this　article,　Mill-Q　water　was　used,　and　the　impact　of　NaOCl　or　NH2Cl　combined　with　ClO2or　ClO2-on　the　yield　of　ClO2-and　ClO2　were　investigated　by　monitoring　the　residual　of　NaOCl,　NH2Cl,　ClO2　and　ClO2-.　It　was　proved　that　when　NaOCl　or　NH2Cl　combined　with　ClO2,　hypochlorousacid　(HOCl)　formed　by　NaOCl　or　NH2Cl　could　react　with　ClO2-,　which　was　the　reason　that　ClO2-yield　reduced　and　ClO2yield　increased,　and　the　increase　in　ClO2yield　exceeded　the　decrease　in　ClO2-yield.　For　the　purpose　of　the　highest　reaction　rate,　the　optimal　ratio　between　NaOCl　and　ClO2　was　3:1,　while　it　was　1:1　between　NH2Cl　and　ClO2.　The　appropriate　ratios　of　residual　NaOCl/NH2Cl　and　ClO2-for　ClO2-complete　removal　were　found　to　be　close　to　the　value　of　1　and　0.5　respectively.　Furthermore,　compared　with　NaOCl,　equivalent　yield　of　NH2Cl　had　much　more　ClO2　residual　yield　when　reacted　with　ClO2,　and　had　faster　reaction　rate　in　any　ratio.　It　can　be　concluded　that　the　generation　of　ClO2-is　typically　much　lower　and　the　residual　of　ClO2　is　much　higher　with　combination　of　ClO2and　NaOCl　or　NH2Cl　when　compared　to　the　use　of　ClO2alone.　And　the　minimum　ratio　between　NaOCl　and　ClO2,　NH2Cl　and　ClO2are　3:1　and　1:1　respectively　when　used　in　micro-polluted　water.