Taking　the　cascaded　H-bridge　(CHB)　inverter　as　the　object　of　study,　the　structure　of　the　inverter　system　is　analyzed　and　the　modulation　strategy　of　the　system　is　investigated.　A　control　strategy　based　on　a　three-phase　cascaded　H-bridge　topology　is　proposed　for　a　PV　grid-connected　inverter　system.　The　scheme　adopts　a　carrier　level　phase-shift　modulation　strategy,　which　can　realize　the　maximum　power　point　tracking　of　the　front-stage　PV　string,　the　control　of　the　grid-connected　current,　and　the　grid-connection　of　the　inverter.　Finally,　the　inverter　with　the　proposed　strategy　is　simulated　in　MATLAB/SIMULINK　environment,　and　the　simulation　results　prove　the　correctness　and　feasibility　of　the　control　strategy.