AnexperimentalwayforthethermalcharacterizationofsemiconductorlasersbasedonI-Vmethodunderpulsedrivingconditionshasbeendeveloped,withwhichthethermalcharacteristicsofstraincompensated1.3μmInAsP/InGaAsPridgewaveguideMQWlaserchipshavebeeninvestigated.Theresultsshowthat,bymeasuringandanalyzingtheI-Vcharacteristicsunderappropriatepulsedrivingconditionsatdifferentheatsinktemperatures,thethermalresistanceofthelaserdiodescouldbeeasilydeduced.Thedrivingcurrentandjunctionvoltagewaveformsofthelaserchipsunderdifferentpulsedrivingconditionsarealsodiscussed.