Using nitromethane， tert-butylamine and formaldehyde as raw materials， a novel melt-casting explosive 5-methylnitrate-1，5-dinitrooxazine （TNOP） was synthesized via condensation and nitration reactions with the total yield of 46.2%. FT-IR， ¹H NMR， ¹³C NMR， elemental analysis and single-crystal testing approaches were conducted to obtain the structure of TNOP， disclosing an orthorhombic crystal structure with a space group of Pbca and the density of 1.722 g·cm^-3. The melting point and thermal decomposition temperature were examined to 110.8 ℃ and 203.5 ℃ using DSC technique， respectively. Furthermore， the detonation velocity and the detonation pressure are predicted to be 8112 m·s^-1 and 29.23 GPa based on calculated enthalpy of solid phase formation （-346.6 kJ·mol^-1）. In addition， an impact sensitivity of 50 J could be obtained for TNOP. By coordinating the energetic groups N—NO₂， C—NO₂ and —ONO₂ and facile synthesis process， TNOP was revealed with high energy， low melting point and low sensitivity， implying that it can be used as potential melt-casting explosive in weapons.