In order to ensure the safety of inflammable and explosive chemical substance such as nitrocellulose (NC) mixtures in the process of handing, storage, and usage, it is necessary to obtain the fire properties of NC with different exterior structures. In present study, fire properties of two commonly used nitrocelluloses with soft fiber structure and white chip structure were investigated by scanning electron microscope (SEM) and the ISO 5660 cone calorimeter. Experimental findings revealed that the most important fire properties such as ignition time, mass loss rate and ash content exhibited significant differences between the two structures of NC. Compared with the soft fiber NC, chip NC possesses a lower fire hazard, and its heat release rate intensity (HRRI) is mainly affected by the sample mass. In addition, oxygen consumption (OC) calorimetry method was compared with thermal chemistry (TC) method based on stoichiometry for HRRI calculation. HRRI results of NC with two structures obtained by these two methods showed a good consistency.