The　paper　proposed　a　multi-stage　PMU　placement　method　to　improve　observability　for　distribution　networks.　A　PMU　optimal　placement　model　based　on　node　measure　index　is　firstly　proposed,　in　which　the　node　measure　index　includes　three　indicators.　The　subjective　and　objective　weights　are　determined　by　AHP　and　entropy　weight　method,　and　the　differences　of　nodes　in　the　distribution　network　are　evaluated,　so　as　to　realize　the　priority　placements　of　important　nodes.　Considering　the　constraints　of　unobservable　depth　and　zero　injection　nodes,　the　rationality　of　optimal　placement　is　improved.　The　linear　model　is　solved　based　on　0-1　integer　programming　algorithm,　and　the　fully　observable　PMU　optimal　placement　results　from　incomplete　observability　to　critical　observability　to　redundancy　are　obtained.　The　simulation　tests　shows　that　the　proposed　method　can　provide　the　multi-stage　optimal　placement　number　and　location　of　PMU.　©　2023　IEEE.