To improve the hazard classification of anhydrous hydrazine， the extremely insensitive detonating substance （EIDS） gap test and external fire test were conducted for the standard packaging anhydrous hydrazine （18 kg and 120 kg） in accordance with the United Nations “Recommendations on the Transport of Dangerous Goods， Manual of Tests and Criteria”. The deflagration process， the highest temperature of the fireball surface and shock wave effect of samples were obtained by a high-speed camera， an infrared thermal imaging and a shock wave pressure acquisition system. The experimental results show that， under external fire conditions， the TNT equivalence of the anhydrous hydrazine-18 kg was 0.724， which was 1930.67 times that of anhydrous hydrazine-120 kg. Under certain conditions， anhydrous hydrazine has obvious explosive properties and can be assigned to Division 1.1 C or Division 1.3 C for different packaging design pressures. The hazard class of anhydrous hydrazine is closely related to the standard packaging design pressure. For safety purposes， the design pressure of packaged anhydrous hydrazine should be properly reduced within the allowable range to effectively reduce its hazard.