To investigate the work condition of the aircraft actuators in high temperatureheat transfer process of the output unit of a cycloidal reducer of the actuator is taken into account by Unigraphics NXHypermesh and ANSYS softwares based on finite element analysis(FEA).The temperature distribution of the output unit is obtained by meshing modelapplying loads and solving discrete problems.Thenthe temperature variation of the output unit is gotten by sampling and processing the data of FEA results.In the endthree main conclusions are drawn.Firstthe heat transfer process of the output units of cycloidal reducers of actuators can be analyzed by FEA efficiently.Secondthe temperature of the rudder and the design position of cycloid gears are two major factors in the operating life of reducers.Thirdthe operating life can be improved by lowering the rudder temperature and installing the cycloidal gear as far as possible away from the heat source.