This paper presents the thermal characteristics of a micro-electro- mechanical deformable thin film mirrors package for the optical modulators used in mobile equipment such as cellphones, lab tops and PDA. One critical factor which affects the performance of the package is the ambient temperature change. To reduce the effect of the ambient temperature change, the temperature control system by a micro heater and a temperature feedback circuit was developed. The thermal characteristics histories were numerically modeled, the results of which were validated by the experimental data. The magnitude of the fluctuation was reduced within 1 C under the controlled system. In addition, required time to reach the steady state temperature was reduced by using the proposed control system.