The purpose of this research is to study the relationship between the manufacturing process of rotor and the efficiency of the induction motor. The composite rotor was made by two kinds of material, aluminum and copper. The general rotor was made by aluminum. We studied how rotor materials, cast aluminum and copper-aluminum composite rotor, affect the current density and efficiency by finite element analysis. The motors, made of two different rotor materials (cast aluminum and copper- aluminum), were tested. Finally, the efficiencies of the motors are discussed.