Although systemic functional linguistics has made fruitful achievements in the theory building of grammatical meta-phor,the issue of the correlation between grammatical metaphor and disciplinarity has not been explored in depth.This paper takes a quantitative and contrastive approach to analyzing the issues of the distribution variance between humanities and sci-ences before throwing some light on the correlation between disciplinarity and the distribution variance,and the reasons why the frequency of experiential metaphor usage in the humanities is significantly lower than that of sciences,the reasons why physics and literature stand at the opposite ends of the variance continuum,and the reasons why the frequency of experiential metaphor usage in the philosophy is unexpectedly higher than that of mathematics.