Abstract: In this paper,to solve the problem of LED heat dissipation,a integrated flat plate heat pipe was designed and the thermal performance was analyzed.An experimental rig was built to test the performance of the flat plate heat pipe.Project was designed to make sure the simulated heat source was insulated well.The simulated heater was fabricated to provide the heat flux which was needed in the experiment.By analyzing uncertainty of measurement,the results show that uncertainty of measurement is in the reasonable range.The influence of the heat power,filling ratio,and working fluid on the thermal performance of the flat plate heat pipe was studied.The experimental results show that the flat heat pipe has good temperature uniformity.The higher the power is,the lower the vapor chamber thermal resistance is.The optimal filling ratio of the flat heat pipe is 40%in the research.Among the three tested working fluids,the heat transfer performance of water proves to be the best.