The effect of long -term blue ligh on the photosynthesis of rice(oryza sativ a L.)seedlingswas studied.Compared to white light tieatment,the blue light treatment induced lowerphotosynthetic rate,photophosphorylation rate of chloroplasts and chlorophyll con-tent,and higher activities of RuBPCase,RuBPO and glycolate oxidase.It is suggestedthat augmented photorespiration in the blue light treatment may be one of the rea-sons for decreased photosynthetic rate.