On the basis of a study of the main factors affecting the goodness—of-fit trend surface，theauthors present a statistical mothod irx which the best power k of trend surface is estimated byusing the data number，2 involved in trend surface analysis，standard deviation d of dataand ex—pected goodness—of—fit．the authors also present a diagram on which thepower of trend surfacecan be determined by various indexes of geochemical exploration．the trend surface chosen ac—cording tO the method presented here has yielded good results in geochemical exploration dataprocessing in some areas of eastern China，which will be important for the study of large quanti-ties of multi—index geochemical anomalies．