Abstract: To study the liquefaction resistance and dynamic properties of tailings in earthquake-prone areas, the ungraded tailings of an upstream tailings pond were chosen as the research object. Firstly, the influence of sedimentation and consolidation methods on the fine content (FC) of the tailings was explored. Then, dynamic triaxial experiments were carried out to investigate the impact of FC on the liquefaction resistance and dynamic properties of the tailings. Moreovre, based on the microstructural characteristics of tailings, the impact of FC on the dynamic properties of tailings was analyzed. Results show that the shallow tailings mainly undergo leaching consolidation and chemical consolidation, while the deep tailings mainly undergo self-weight consolidation, and FC increases with increasing sampling depth. The liquefaction resistance of the tailings decreases initially and then increases with increasing FC. A smaller FC results in a higher liquefaction resistance in tailings and a faster cyclic stress ratio attenuation, while the variation of FC has little impact on the dynamic pore water pressure ratio. As FC increases, the dynamic shear modulus of the tailings decreases initially and then increases, the damping ratio initially increases and then decreases. The dynamic properties of the tailings gradually shifted from coarse particle control to fine particle control, with a critical threshold of about 60% for FC. The research results can provide a theoretical basis for stability evaluation of tailings ponds in earthquake-prone areas, as well as the dynamic analysis of tailings.