Water　samples　of　secondary　effluent　from　an　urban　wastewater　treatment　plant　are　applied　with　laboratory　experimental　method.　The　efficacy　of　disinfection　and　control　performance　of　trihalomethane　production　are　investigated　in　the　pretreatment　process　with　individual　application　of　chlorine,　chloramines　and　potassium　permanganate,　and　with　combined　application　of　potassium　permanganate　with　chlorine　or　chloramines.　The　results　show　that　the　effectiveness　of　chlorine　disinfection　is　extremely　affected　by　seriously　polluted　water,　especially　the　wastewater　with　high　contents　of　chlorine-consumed　matters.　The　effect　of　chloramines　disinfection　is　better　than　that　of　chlorine　disinfection.　The　effect　of　combined　application　of　potassium　permanganate　with　chlorine　or　chloramines　is　clearly　better　than　that　of　individual　chlorine　or　chloramines　disinfection,　and　the　production　of　trihalomethane　is　reduced　additionally.　Therefore,　the　pretreatment　process　of　combined　application　of　potassium　permanganate　with　chlorine　or　chloramines　is　an　effective　method　of　improving　water　quality　of　wastewater　reuse.