This study carries on zircon U-Pb dating in LA-ICP-MS and Rb-Sr dating in quartz samples from porphyritic monzonitic granite and ore body in Xishan block, so to determine the formation time of Xishan W-Sn deposit and the wall rocks. The yielded zircon U-Pb age is 103±3Ma, and the quartz Rb-Sr iscochron plots give an age of 93±11Ma, which are identical within the margin of error. This indicates a coupled relationship in time and space between late-stage granite and deposits in Xishan block, which occurred during Late Cretaceous. The tectonic setting of Xishan block and deposits may be related to the voluminous magmatic activities caused by the extension of lithosphere in Nanling region in Late Cretaceous.