To evaluate the vulnerability of explosive charge, a roast bomb structure with different sealing conditions (state 1:the end cover is 2 steel plugs and 2 pressure membranes.state 2:the end cover is 4 pressure membranes) and thermal conductivity of coating layer (state 3:the end cover is 4 pressure membranes, hollow glass microspheres (HGMs) partially instead of the silicone rubber in the coating layer) was designed.The response characteristics of octogen (HMX)-based aluminized explosive (HAE) under the condition of external fire with liquid fuel were studied.Results show that the pressure membrane of end cover and HGMs coating layer can achieve the purpose of reducing the vulnerability of explosive charge.The effect of pressure relief area and thermal conductivity of coating layer on the fast cook-off characteristics of explosive charge is different.The response level of roast bomb of decreasing the thermal conductivity of coating layer (projectile body is complete, charge and end cover sprayed, and the charge is not steady combustion) is lower than that of roast bomb with the change of sealing conditions (projectile body is complete, the charge is steady combustion).When the ratio of pressure relief area to the surface area of HAE charge is greater than 0.015, the explosive charge reveals in steady combustion state.When the content of the HGMs exceeds 5%, the end cover of roast bomb and explosive charge are sprayed out, and the structure of the explosive charge is integrated and the combustion state does not occur.