Abstract: Polytetrahydrofuran ether glycol (PTMEG) as a toughening agent was introduced into the structure of the tripolycyanamide formaldehyde(MF) resin to carry out the chemical modification. Then, PTMEG/MF resin was fully mixed and stirred with the surfactant, foaming agent, nucleating agent and so forth.Finally, the PTMEG/MF foam board was obtained by thermal foaming. The synthesis process of MF resin was optimized by using polyformaldehyde instead of formaldehyde solution to control the solid content of resin precursor. The effects of polycondensation time and solid content on the density of PTMEG/MF foam board were studied. The chemical structure, micro morphology, mechanical properties and thermal decomposition temperature of PTMEG/MF foam board were examined and analyzed by H-nuclear magnetic resonance (¹H-NMR), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope(SEM), universal material testing machine, and thermal gravimetric analyzer. Results showed that when the polycondensation time was 45 min and the solid content was 60%, PTMEG/MF foam board showed good performance. PTMEG was successfully implanted into MF network structure, forming a stable three-dimensional structure. The tensile strength of the PTMEG/MF rigid foam board reached 6.72 MPa and the thermal decomposition temperature was 346℃. When the mass ratio of PTMEG to MF was 15%, the PTMEG/MF rigid foam board showed good comprehensive performance with regular opening hole structure, good mechanical properties, and with no slagging on the surface. The PTMEG/MF foam board prepared by this method can be applied to the flame retardant and thermal insulation material.