Abstract: Based on fhe surnmarization of historical data of fhe 1337 Huailai (old) Ms6.5 earfhquake and fhe new data obained during surveying and investigating the earthquake from 1992 to 1993, Some parameteres are discussed for this earthquake. The area with intensity VⅡ is outlined and the coutour of seismic intensity Vl is reestimated for the earthquke, and the epicenter (40°3o'N, 115°30'E) is relocated. The study of the earthquake has some significance for the mid-long term earthquake tendency analysis in thw CapitaI Circle area, and for the evaluation of seismic safety in the area.