[Objective] The effects of restoration years on plant diversity and soil chemical characteristics of alpine metal mine dumps were studied in order to provide scientific guidances for further exploring the plant succession trends and optimizing the plant restoration process of alpine mine dumps. [Methods] The study was conducted at the Delny copper mine, Guoluo Xizang Autonomous Prefecture, Qinghai Province. Plant species composition and diversity and soil chemical properties of ten alpine metal mine dump slopes varying in recovery years (1—12 years) were measured by quadrat survey and soil chemical analysis. Relationships between four α plant diversity indexes (Patrick richness index, etc.), eight soil chemical property indexes (total nitrogen, etc.) and number of recovery years were determined. [Results] The number of families, genera, and species of plants at the dump sites increased with increasing number of recovery years due to the continuous invasion of natural plants. There were differences in plant species composition and community characteristics of the dumps in different years. The Patrick richness index increased as a power function as number of recovery years increased. The Shannon-Wiener diversity index, Simpson diversity index, and Pielou evenness index initially increased with increasing recovery year, and then decreased, and all indexes changed with time following quadratic relationships. The contents of total nitrogen, total phosphorus, total potassium, alkaline hydrolysis nitrogen, and rapidly available phosphorus initially increased with increasing number of recovery years, and then decreased. The contents of rapidly available potassium and organic matter increased as a power function as number of recovery years increased. pH value decreased as number of recovery years increased. The four α plant diversity indexes were positively correlated with the contents of soil total nitrogen, total phosphorus, total potassium, alkaline hydrolysis nitrogen, rapidly available potassium, and organic matter, but negatively correlated with the contents of rapidly available phosphorus and with the pH values. [Conclusion] When the recovery period was 12 years, the plants in the dump area were still in the successional development stage and had not yet reached a stable state. There was an obvious interaction between plant succession and soil nutrients. It is suggested that high nitrogen, high phosphorus and low potassium slow release compound fertilizer should be used for plant restoration in mine dumps.