In-depth　study　of　the　DC　side　voltage　control　of　the　star　connection　cascaded　H-bridge　multilevel　static　var　generator　has　been　made　in　this　study.　Moreover,　a　three-layer　DC　side　voltage　control　system　has　been　established.　The　first　layer　is　overall　DC　side　voltage　control.　The　overall　DC　side　voltage　of　three　phases　A,　B　and　C　is　maintained　constant　through　generating　fundamental　positive　sequence　active　current.　The　second　layer　is　balancing　control　between　three　phases.　Through　injecting　zero　sequence　voltage　into　the　voltage　command,　the　authors　can　redistribute　three-phase　active　power,　in　order　to　maintain　three-phase　DC　side　voltages　balanced;　in　this　method,　fast　dynamic　control　can　be　achieved　through　feeding　forward　the　power　that　grid　voltage　and　converter　current　produce.　The　third　layer　is　balancing　control　between　modules　of　each　phase.　Through　adjusting　voltage　commands　of　H-bridge　modules　of　each　phase　along　the　direction　of　the　converter　current,　they　can　redistribute　the　active　power　absorbed　by　each　module,　in　order　to　ensure　that　DC　side　voltages　of　modules　of　each　phase　are　equal　to　each　other.　Experimental　results　verify　the　correctness　and　reliability　of　the　proposed　control　system　in　the　end.