Abstract: In the paper an approach of register analysis based on conceptual mapping model is designed to compare WAR metaphor use in business discourse and health discourse.It is found that the latter uses more,more dynamic and more specific metaphors on the linguistic level.On the conceptual level,WAR metaphoric mapping in the former highlights the strategic nature of wars while that of the latter, the suddenness and violence of the war process.On the communicative level, WAR metaphoric mapping in the former conveys the evaluative meaning{Neutral:Affect——Desire}while that of the latter, the evaluative meaning{Negative:Judgment——Danger}.The register analysis under discussion reveals register differences through comparing metaphoric mapping on the linguistic,conceptual and communicative levels.