Amicrogrid　mode　control　system　including　power　control,　amplitude　control　and　phase　control　was　designed　for　smooth　switch　between　grid-connected　and　islanded　microgrid　modes　with　master-slave　control.　A　load　transfer　strategy　on　active　isolating　was　introduced　to　reduce　impact　on　master　control.　A　novel　phase　control　method　without　PLL　was　proposed.　Compared　to　conventional　method,　the　proposed　method　with　simple　structure　not　only　achieved　pre-synchronization　control　of　islanded　microgrid　to　main　grid,　butalso　ensured　frequency　stabilityand　phase　continuity　during　control　mode　transition.　A　simulation　platform　of　a　microgrid　was　established,　and　transients　of　passive　isolating,　active　isolating　and　transition　from　islanded　to　grid-connected　mode　were　analyzed.It　verified　validity　and　superiority　of　the　proposed　control　strategy.　©　2016,　Power　System　Technology　Press.　All　right　reserved.