On the basis of textural research on the historical earthquake data and the field investigation of 1219 A.D. Guyuan earthquake, the authors suggest that there is only onestrong earthquake occurred in Guyuan area in 1219 A.D., instead of two or three strong earthquakes. The authors further suggest that the earthquake parameters reported in the present earthquake catalogs are not definite and should be modified. The occurrence time of this earthquake should be about 11 am, August 7 (local time), 1219 A.D. and the heavily-damaged area, the intensity Ⅷ area, should be located among the regions of Guyuan, Pingliang and Longde County. The epicenter area should be near Guyuan Town. The magnitude of this earthquake is about 7 and the epicenter intensity should be>Ⅸ. The major heavily-damaged area elongates in NNW-SSE, which is approximately consistent with the strike of the Liupanshan thrust fault zone. The new tectonic activity of the Liupanshan thrust fault zone resulted in the M7 Guyuan earthquake in 1219 A.D.
