Abstract: During the heat treatment of thin walls of TC4 titanium alloy for aviation, the process affected is prone to oxidation and intercrystal corrosion. If heated with other materials, it is easy to cocrystalize with the Fe element in it, forming a low melting point eutectic reaction product that melts at low temperature. The purpose of this paper is to study the effect of Fe element in different materials on the melting temperature of TC4 titanium alloy. Select typical aviation materials with different Fe content of GH4169, 06Cr18Ni9 and TC4, and comparatively analyzed the tissue morphology and eutectic reaction product FeTi of the three groups of GH4169+TC4, 06Cro18Ni9+TC4 and GH4169+06Cr18Ni9 after being heat treated at 1170℃with a temperature of 40min. The composition of the eutectic product FeTi produced by heat treatment was analyzed using a Bruker Sititan 300 spectrometer and an Axio Observer Zeiss micrograph. The results showed that when the temperature rose to the FeTi cocrystallization temperature point（the minimum cocrystallizing temperature was 1085℃）, The eutectic reaction between Fe and Ti in the low melting point eutectic region of TC4 titanium alloy occurs in different samples to form the eutectic reaction compound FeTi, the higher the Fe content, the more obvious the reaction. and as the temperature increased,the FeTi eutectic reaction organization melted to form a liquid phase, thereby reducing the melting temperature of the TC4 titanium alloy. This study can provide theoretical guidance for vacuum heat treatment of TC4 titanium alloy components used in aviation.