A　SWMM　(Storm　water　management　model)-based　method　for　the　adjustment　of　rain-off　model　parameters　is　proposed　to　realize　the　equivalent　design　conditions　in　pipe　network　design　calibration　with　hydraulic　model.　The　method　proceeds　from　the　basic　principle　of　Rational　Method,　and　takes　the　assumption　of　runoff　curves　with　time　as　the　basis.　By　simulating　the　runoff　catchment　through　constant　rainfall　pattern,　the　principle　of　equivalent　can　be　judged　by　whether　the　features　of　the　simulated　runoff　curves　matched　those　of　the　assumption　with　Rational　Method.　Case　study　has　verified　the　feasibility　of　the　proposed　method.　Meanwhile,　to　simplify　the　manual　operation　in　parameters　adjustment,　an　improved　particle　swarm　optimization　(PSO)　has　been　put　forward　to　complete　the　process　automatically.　©,　2015,　Harbin　Institute　of　Technology.　All　right　reserved.