The significance of overload in power system has increased substantially due to of consumption and ambient temperature rise. An important consideration when evaluating the impact of overload is their on power system ambient tem-and load. Transformers are major components in power systems. The increase useful lifetime and hence abnormal temperature rise. Existing standards give a procedure to determine the capability of an existing transformers subject to overload problem and ambient temperature rise based on conservative assumptions .in addition, the temperature oil rise of power transformer due to overloading and ambient temperature are estimated based on power and cooling system, and the average daily or monthly temperatures to which a transformer would be subjected while in service. it is the purpose of this research of this effort to quantify the decreased life time due to overloading and the corresponding temperature rise in transformers. This is accomplished using a 2-D FEMLAB Model adapted for cooling simulation in power transformers.