Ningwu basin is an important ore district in the Middle-Lower Reaches of the Yangtze River belt, China. There are several decades of subvolcanic rocks – related iron deposits in the basin, which is well known as porphyry iron deposits in China. Washan iron deposit is one of representative porphyry iron deposit in Ningwu ore district. Detail zircon U-Pb age measurements were performed on the two plutons in Washan iron deposit area in order to constrain the rock-forming and ore-forming ages. The zircon U-Pb age is 131.7±0.7Ma for gabbro-diorite porphyry which is the host rock for the mineralization, and the zircon U-Pb age is 126.1±0.5Ma for granodiorite porphyry which cut across the ore body. According to the relationship between petrogenesis and mineralization, the ages of mineralization of Washan iron deposit is in the 131.7 - 126.1Ma. It belongs to the Early Cretaceous. The mineralization associated with early magmatism in Ningwu basin is proposed to occur in an extensional tectonic regime, possibly induced by lithospheric thinning.