Wetland nature reserve is a special type of terrestrial reserves. Its conservation effectiveness is determined by both the management intensity inside and the hydrological status outside the reserve. Therefore, the ecological function differences inside and outside reserves is an integrated indictor for assessing conservation effectiveness. Based on the land use map created from Landsat-TM satellite image of the year 2004 and 1∶50000 Digital Elevation Model (DEM) data of the year 2002 in Jiansanjiang, Helongjiang province, the catchments that the wetland reserves belong to were determined as their hydrological sensitive zones by SWAT (Soil and Water Assessment Tool) hydrological model. The ecological function indices of wetland reserves and their corresponding hydrological sensitive zones were calculated though expert consultation and a value assessment function of wetland ecosystem services. The results showed that the ecological functions of national wetland reserves were better than those of local government′s reserves in general. However, the wetland ecological functions of hydrological sensitive zones of the former were not always better than those of the latter. Meanwhile, Clustering Analysis showed that the wetland ecological functions of adjacent reserves′ were similar in Nongjiang-Bielahonghe watershed. But Correlation Analysis found a remarkable positive correlation between the wetland ecological function indices of local government′s reserves and their corresponding hydrological sensitive zones. In conclusion, although conservation effectiveness of wetland reserve is determined by both management intensity inside and the hydrological status outside, the former plays a key role and should be reinforced in practice.