The　modified　LCL　(MLCL)　is　commonly　applied　in　photovoltaic　(PV)　string　inverters　to　suppress　the　leakage　current　and　enhance　the　electromagnetic　interference　(EMI)　performance　of　the　grid　current.　However,　the　potential　risk　of　resonance　appears　in　the　common　mode　(CM)　loop,　which　was　caused　by　the　MLCL　filter.　In　this　article,　the　CM　model　of　the　inverter　is　first　built　considering　the　inductance　saturation.　It　is　found　that　the　variable　inductor　brings　phase　margin　decreasing　problem　and　additional　resonance　points　in　the　CM　loop.　To　suppress　the　CM　resonance　(CMR),　novel　passive　and　active　damping　strategies　are　explored　in　this　article.　The　improved　passive　damping　(IPD)　strategy　is　realized　by　introducing　a　paralleled　RC　unit,　which　greatly　reduces　the　damping　resistor　losses　without　affecting　the　damping　performance.　Besides,　a　novel　active　damping　(NAD)　strategy　is　proposed　to　compensate　the　time　delay　and　to　raise　the　phase　margin.　Moreover,　considering　the　gradient　mutation　issue　brought　by　the　discontinuous　pulsewidth　modulation　(DPWM)　scheme,　an　antisaturation　PWM　(ASPWM)　scheme　is　applied　to　eliminate　the　oscillation.　Finally,　experiments　are　conducted　on　an　80-kW　PV　string　inverter.　After　applying　the　proposed　CMR　damping　strategy　with　the　ASPWM　scheme,　CMR　is　fully　eliminated　in　the　whole　power　range　despite　the　grid　condition.