As an important thermodynamic parameter of explosives， thermal conductivity significantly affects the ignition response characteristics of explosive charge. In order to quickly and effectively obtain the thermal conductivity of explosives without tests， an axisymmetric heat conduction theoretical model of typical cylindrical charge structure is established， and its steady-state analytical solution is derived. Also， a method for calculating the thermal conductivity of explosives is proposed based on the slow cook-off experimental data. The thermal conductivity of a new type of insensitive explosive， GOL-1（HMX/Al/AP/Binder）， is determined. The numerical simulation results of the ignition response of small-size charge structure under typical cook-off conditions shows that the calculated results of the charge center temperature-time curves at different heating rates are basically consistent with the experimental results， and the deviations of ignition temperature at charge center and ignition time between the calculated and experimental results are 2.27% and 1.12% at most， which indicates the effectiveness of the thermal conductivity of the GOL-1 and the feasibility of the numerical simulation method. The established calculation method reveals the thermal conductivity characteristics and rules based on the temperature-time curves of slow cook-off experiments， which is more suitable for calculating the thermal conductivity of explosives compared with volume-weighted method and string or parallel heat conduction model. In the absence of experimental data for determining the thermal conductivity of new explosives， this method is an effective determination method， providing a basic parameter for the design and evaluation of thermal safety of ammunition and promoting the development of digital design and quantitative evaluation of safe ammunition.