With the rapid development of the micro projector, the problems of its power consumption and heat dissipation have been increasingly serious. The thermal design can improve its reliability and cut costs at the design stage. This article selects DLP built-in micro projector provided by TI Company to analyze, uses thermal analysis software Flotherm to get the temperature distribution and temperature curves of the measuring points in the steady state, then compares the simulation results of the cooling optimization with the numerical analysis, which reduces the temperatures of thermal sources and shells. The conclusion supplies new theoretical basis on the development of mobile phones integrated with the projection function.