It has been considered that the Environmental database system in coastal area is necessary to be established. For modeling a marine ecosystem of coastal sea area many kind of environmental parameters are necessary. Especially parameters determined from actual sea/marine environments are usually exclusive to the sea area concerned. In Osaka bay sea area, there have been being carried out systematic observations on seawater qualities including some environmental characteristics for more than half a century, by fisheries and environmental departments of local governments. The authors obtained those observation results and have been carrying out fundamental studies for developing an environmental database system using those results. In the present paper, they propose a method for explaining the temporal transition of environmental characteristics introducing methods of Auto-Regress ional Analysis model (AR-model) and Vector AR-model. They applied the long-term environmental data to these models and obtained successful results that explain the transition of environmental characteristics in time. They also obtained agreeable results that show interaction between environmental items.