Taking Nuozhadu hydropower station and its effected Nature Reserve for example, we study the change and its gradient changes in landscape structure caused from hydroelectric project based on GIS and buffer analysis. We choose fractal dimension, patch density, dominance index, etc to quantify the landscape pattern change and link them to naturality, diversity, stability and anthropogenic interference of ecosystem to establish an evaluation system, which is used to estimate the ecological condition of the Nature Reserve. The value of each index is determined by the evaluation system, the weight percentage was decided through Analytical Hierarchy Process (AHP). The result show that vegetation type in different buffer zone appeared gradient changes. Hydroelectric project might have significant impacts on some type of forest such as monsoon evergreen broadleaved forest, bamboo grove and deciduous seasonal rain forest. And the hydroelectric project might enhance landscape heterogeneity intensified. Landscape pattern changed significantly especially within 800-meter buffer zone. The ecological evaluation show, that hydroelectric project may slightly deteriorate ecological condition.