There are no reports before about volcanic rocks in Dahongyu Formation, Changchong System of Ming Tombs area. One layer of tuffite was discovered by tile authors. The tuffite was composed of three different colour beds.The clay mineral is mainly montmorillonite. The pyroclastic minerals include sanidine in thick-plate shape and euhedra zircon with short cone-shaped twin.Obvious welded tuff texture and pseu-flowage structure have been found in tile tuffite, tuffite contains higher K_2O contentTherefore, the authors consider that this layer could be tuffite. Its attitude is consistent with the sedimentary formations of Dahongyu Formation,Hence, the tuffite should be ejected in the time of forming Dahongyu Formation.