The research on low-sensitivity gun propellants has a vital impact on the survivability and safety performance of weapon system. Gun propellant （IM） with nitrocellulose （NC） and glycidyl azide polymer （GAP） as binder was prepared. N-butyl-N- nitramine （Bu-NENA） was used as low sensitive energetic plasticizer， hexogen （RDX） was used as high-energy filler and graphite as additive of thermal conductive. The physicochemical， combustion， mechanical， and sensitivity properties of the IM gun propellant were studied， and the insensitivity properties were further studied by slow cook-off， fast cook-off， bullet impact， fragment impact and sympathetic detonation tests. Results showed that the gun propellant had stable combustion performance， and the impetus was1050 kJ·kg^-1. Theoretical explosion temperature was 2677 K. The impact strength and the compressive strength were 8.2 kJ·m^-2 and 131.5 MPa at -40 ℃， respectively. The sensitivity of the gun propellant （H₅₀=62.62 cm，P=28%，V₅₀=1.95 kV） was greatly reduced compared with TEGN gun propellants（H₅₀=16.33 cm，P=100%，V₅₀=2.02 kV）. Moreover， only combustion reactions were observed in slow cook-off， fast cook-off， bullet impact， fragment impact and sympathetic detonation tests. It demonstrated that the prepared gun propellants possessed good low vulnerability characteristics.