TWTA(Traveling Wave Tube Amplifier) is a device the density of the fever is high. Thermal analysis has purpose to check heat dissipation of TWTA is smooth with sufficient safety margin. Excessive design to increase the weight of unwanted can be occurred if only thermal safety aspects are considered. In addition, it seems to be risky that reduce the weight of TWTA after thermal analysis just is done. Therefore, in this study temperature test was carried out in parallel with the thermal analysis to reduce the weight of the TWTA while achieving thermal safety margin. Thermal stability can be kept estimating the temperature of the area measured temperature using the thermal analysis results. In this study, using a thermo couple and the hybrid recorder measured the temperature of TWTA, and thermal analysis program was used NXI TMG reflecting curved shape without modification.