Microbial　inactivation　efficacy　of　many　pre-oxidants　can　be　influenced　by　pH　value　of　polluted　water.　Microbial　inactivation　effects　are　compared　with　individual　application　process　of　chlorine,　chloramines　or　potassium　permanganate,　and　with　combined　application　process　of　potassium　permanganate　with　chlorine　or　chloramines,　to　investigate　more　effective　pre-oxidants.　The　results　show　that　the　inactivation　effects　of　several　pre-oxidants　are　interfered　to　different　degrees　by　pH　value.　The　advantage　of　combined　application　process　of　potassium　permanganate　with　chlorine　or　chloramines　become　more　obvious　with　increasing　of　pH　value,　compared　with　individual　application　process　of　chlorine　and　chloramines　under　same　total　dosage.　The　inactivation　effects　are　increased　0.14　and　0.25　logarithmic　grades　with　pH　=　7,　respectively;　and　0.95　and　0.55　logarithmic　grades　with　pH　=　9,　respectively.　Because　pH　value　of　natural　water　is　normally　within　range　of　neutral　or　weak　alkaline,　a　newly　safe　pre-oxidation　technique　of　the　combined　application　process　of　potassium　permanganate　with　chlorine　or　chloramines　of　the　is　presented　for　polluted　water　treatment.