Definition and Assessment of River Ecosystem Health

River ecosystem makes an important role in people health and development of society and economy.This paper introduced the conception of ecosystem health and took the river ecosystem for example to diversify estimate index to index of instinctual characteristic and index of deveJ.opment of society and people health.The paper also emphasized the zoology index that belongs to ecosystem instinctual characteristic and introduced the estimate methods that used algae,benthic invertebrate and fish as indicator.The difficulties of estimating ecosystem were pointed out at the end.