Abstract: Based on a case Study of the Fenlingshan volcanic apparatus, the formation ages of volcanic rocks of the Qingshan Formation in the Jiaolai Basin have been determined accurately by employing the highly precise 40Ar-39Ar dating technique． Investigation results demonstrate that the age of intermediate to alkaline potash-rich volcanic rocks of the first cycle of the Qingshan Formation is 109.9±0.6 Ma: and the age of the acidic rhyolitic volcanic rocks of the second cycle of the Qingshan Formation is 108.2±0.6Ma．It is thus evidenced that volcanic rocks of the Qingshan Formation in the Jiaolai volcanic Basin are products of Early Cretaceous magmatism. The ages of volcanic rocks of the Qingshan Formation in Shandong province display a progressively younger tendency eastwards，suggesting that the Mesozoic subduction of the Izanagi plate towards the Eurasian plate is the main dynamic factor that controlled the volcanism in this region.