The grey system theory was employed to analyze the effects of five climate factors on the forest fire frequency and area covering from 1991 to 2002. The grey orders indicated that the contribution degrees of climate factors to fire frequency were: monthly mean relative humidity > daily insolation percentage > monthly mean temperature > daily cumulative irradiance > monthly cumulative precipitation。 The orders for fire area were: daily insolation percentage > monthly mean relative humidity>monthly mean temperature > daily cumulative irradiance > monthly cumulative precipitation. The data further suggest that monthly mean relative humidity and daily insolation percentage play a more important role on forest fire frequency and area than other climate factors in Mt. Dadu area.