Considering widely use of three-phase induction motors in industry, commercial and residential applications and the probability that they may exposed to the unbalanced voltages, it is very important to clarify the effects of voltage unbalance on the performance of them.In this paper, authors simulated a three phase squirrel cage induction motor under six types of unbalanced voltages with same VUF combined with under voltage or over voltage in one or more phases using two-dimensional finite element method. Electromagnetic torque of the mentioned motor analyzed and effects of voltage unbalance on its average torque and torque ripple investigated and also, emphasized to detect unbalance condition, torque frequency analysis can be used.