Abstract: In this paper the ecological benefits of complex ecosystem of rice-reed-fish in the mire region of the Sanjiang Plain are presented according to firsthand observations in the field in four years and chemical analysis data of soil,water and product of the system. This system utilizes water resource comprehensively and cyclically and raises its utilization rate.It is able to regulate the runoff of river and maintain the regional water balance,so,it has become an ecological defence for farmland around the complex ecosystem.It makes the air relative humidity rise,similar to mire function so that it prevents regional environment from drying.Some field management measures,ploughing amd irrigatiom in spring,improve thermal regime of soil and appear a positive effect for soil temperature in the reedland.This system also owns ecological function in conserving regional ecological environment and raising its quality.It has ability to clear up many kinds of organic and inorganic pollutant from water and soil.The soil fertility of this system has been increased in comparison with original mire.This system provides a ideal habitat of propagation,foraging,nidation and fattening for wild precious mire animals,both the quantity and composition of mire animal have increased obviously after exploiting mire in this way.The system plays an important role in conserving rare mire animals and maintaining ecological balance of mire region.This exploitative model improves the productive force as compared with mire and raises the land-control rate in this area.We believe that exploiting mire in the way of growing rice and reed and fishing is one of the ideal models for wide distributional region of mire.It creates a new path for our country to develop mire.