The formation of the Gejiu tin ore deposits experienced three generation mineralizations, which were, in an ascending order, the seabed basic volcano-sedimentary mineralization in the Indosinian epoch (metallogenetic series Ⅰ), the seabed exhalative hydrothermal sedimentary mineralization in the Indosinian epoch (metallogenetic series Ⅱ) and the superimposed granitism-reformed mineralization in the Yanshanian epoch (metallogenetic series Ⅲ). The paper analyzed metallogenetic ages of the above-mentioned metallogenetic series by means of Ar-Ar, K-Ar and Pb-Pb methods. The dating results showed that the ages of metallogenetic seriesⅠby Ar-Ar, K-Ar and Pb-Pb methods yielded from 95.93±5.41 to 123.91±15.41 Ma, 112.50±2.25 Ma and from 210 to 240 Ma respectively. The ages of metallogenetic seriesⅡ yielded from 191.81±2.26 to 205.11±4.38 Ma, 186.01±3.72 Ma and from 200 to 230 Ma respectively. The ages of metallogenetic series Ⅲ yielded from 83.23±2.07 to 85.22±2.38 Ma, 43.49±0.87 Ma and from 83 to 116 Ma respectively. In other words, the Gejiu tin ore deposit should be a mine with multiple phases of mineralization.