Abstract: Objective To analyze the levels of biochemical components in saliva of children and adolescents with stress after sudden natural disasters. Methods A total of 236 children and adolescents from Wenchuan earthquake region were divided into children group and adolescent group according to the regions where they lived and their ages.Levels of biochemical components in their saliva were measured with a Hitachi 7600 biochemical analyzer. Results The Ca levels were lower while the SA,Mg and Cl levels were higher in saliva of adolescents than in children from Xuankou Town（P＜0.05）.Multi-factor analysis showed that the Mg,Na,Cl and SA levels were higher in children from Shuimo Town than in adolescents from Xuankou Town（P＜0.05）. Conclusion Sudden natural disasters can change the levels of biochemical components in saliva of children and adolescents,which may be correlated with the severity of stress.