Based　on　finite　element　analysis　to　electromagnetic　field　of　Brushless　DC　Motor　(BLDCM),　stator　winding　inductance　curves　relative　to　different　rotor　position　due　to　the　saturation　effect　are　showed.　And　then　current　response　regularity　on　DC　bus　of　BLDCM　power　driver　is　analyzed　when　different　voltage　vectors　are　applied　to　the　stator　windings.　The　judgment　rules　and　implementation　steps　for　high　resolution　rotor　zero　initial　position　are　presented　and　so　rotor　positioning　error　is　less　than　7.5　degree　electrical　angle.　The　method　is　also　applicable　to　BLDCM　running　at　low　speed,　so　that　reliable　operation　of　BLDCM　is　realized　without　oscillation　in　starting　and　low　speed.　Prototype　test　was　made　to　prove　the　feasibility　of　the　method.