The very thick Early Paleozoic volcanic-flysch formation forms the main part of Laji Mountain , where occur polymetallic ore deposits dominated by copper and gold ores. The authors have studied the opening and closing evolution of the volcanic basin by means of geological and geo-chemical methods. In addition, the relation of the openning and closing to the mineralization of copper and gold deposits was further explored. Results indicate that the volcanic basin experienced three cycles of opening and closing of the lithosphere and that the source beds of copper and gold deposits were formed in the periods of opening, while remobilization and enrichment of copper and gold were completed during the closing. The conclusion may help us to understand well the characteristics of the evolution of erogenic belts and mineralization.