Abstract: Against the limitations of flexible composite pipe in harsh field conditions, the flexible composite pipe consisting of PE80 inner pipe and PET fiber reinforced pipe is adopted. The performances of inner pipe, reinforced pipe and the whole composite pipe under high temperature are analyzed by using HTHP pot, differential thermal scanner, thermal deformation and vicat softening temperature tester, infrared spectrometer, universal testing machine and pressure equipments. The results show that high temperature has little impact on environmental compatibility, mechanical properties and structural composition of PE80 inner pipe, but significant impact on tensile properties and the entire hydrostatic burst strength values of PET fiber reinforced pipe. The flexible composite pipe fails in 1 000 hr survival testing, therefore, it is not recommended at temperatures above 95 ℃.