In powder packing, it is essential to understand the packing structure of different powders. In this study, we numerically analyzed the packing structure of flexible rod particles using a discrete element method. We quantitatively evaluated the packing structure using the aspect ratio, flexibility, and surface energy of the flexible rod particles and determined the effects of these factors on the packing structure in terms of the radial distribution function, coordination number, and porosity. The flexible rod particles used for powder packing were simulated using a worm-like chain model, in which multiple spherical particles were connected in the form of a rod. The surface energy acting on the particles was represented using the Johnson-Kendall-Roberts model. The packing structure of the particles was quantitatively analyzed by filling a cylindrical container with the particles. The aforementioned factors affected the packing structure to different extents depending on the conditions. When the aspect ratio of the particles was high, the flexibility significantly affected the packing structure. However, when the aspect ratio of the particles was low, the effect of the surface energy was predominant. (C) 2019 Elsevier B.V. All rights reserved.