Focused　on　the　parameters　excursions　of　controller,　a　control　strategy　of　non-fragile　H∞　control　based　on　Delta　operator　theory　for　PMLSM　is　illustrated　in　this　paper.　Then　the　characteristics　of　the　designed　controller　is　compared　with　that　of　the　controllers　which　are　designed　with　Z　transform　method　and　continous　model.　Through　the　analysis　of　closed-loop　pole,　the　results　show　that　the　Delta　operator　control　system　is　stable　and　of　the　expected　H∞　performance,　it　also　can　implement　exactly　tracking　and　reject　the　interference　effectively　in　the　case　of　fast　sampling　even　if　the　parameters　of　the　controlled　object　are　of　variations,　while　the　Z　transformation　control　system　will　be　unstable.　The　results　also　show　that　when　the　sampling　time　is　reduced　to　zero,　the　trend　of　the　parameters　of　the　designed　controller　based　on　Delta　operator　theory　towards　that　based　on　continous　model.