A　simple　but　effective　sensorless　control　technique　for　PMSM　is　presented　in　order　to　solve　the　failure　of　low　speed　operation　in　traditional　technique.　A　high　frequency　voltage　is　injected　into　the　motor　and　causes　a　little　change　of　current　signal　because　of　the　anisotropy　of　the　machine.　By　processing　the　current　in　the　armature,　rotor　position　and　speed　can　be　calculated　accurately.　A　new　way　to　observe　the　original　rotor　position　when　PMSM　is　standstill　is　also　presented　in　order　to　solve　the　starting　problem　of　PMSM.　The　results　of　simulation　show　that　this　method　can　work　feasibly　and　effectively.