Abstract: This paper discusses the possible chemical reactions and its condition of Tungsten Rhenium thermocouple in nitrogen gas at high temperature containing graphite by thermodynamic calculation and energy dispersive spectroscopy(EDS) test.The results show that the complicated chemical reactions among nitrogen gas, graphite and W-Re are the reasons of W-Re thermocouple failure at high temperature.In the assemble process of Tungsten Rhenium thermocouple, it is not suitable for SiC to be used as insulated materials for W-Re thermocouple and tries to avoid the crossed contamination among graphite quartz sand and W-Re.