The Stoner‐Wohlfarth model and the chain‐of‐spheres fanning model are used to calculate temperature dependence of the coercivity of acicular single‐domain particles by taking thermal effect into consideration. Coercivity of the particles is evaluated by summing up the contributions of shape anisotropy, magnetocrystalline anisotropy and magnetostrictive anisotropy. The coercivities of randomly assembled Fe3O4particles above the transition point (119°K) and below room temperature are calculated and compared with the published experimental data.