Saccharina japonica is widely used as raw material for chemical and pharmaceutical application, due to its diverse metabolic compounds: alginate, fucoidan, mannitol and laminarin etc. The contents and structure of these metabolites vary according to different developmental periods and different tissue sites. The aim of this study is to explore the transcriptional profiles of genes involved in metabolic pathways and find the regulatory mechanism in carbohydrate biosynthesis in the kelp.