This　paper　presents　the　maximum　efficiency　controlling　strategy　for　induction　machine.　The　Theoretical　and　experimental　study　have　been　done　to　investigate　the　relationship　between　the　highest　efficiency　and　the　rate　of　iron　loss　to　copper　loss　in　this　paper.　The　significant　equations　have　been　derived　and　highest　efficiency　controlling　algorithm　will　be　introduced.　The　method　to　get　control　parameters　from　experiment　is　also　discussed　here.