Based on the current international popular pressure-state-response(PSR)analytical model, an evaluation system for the ecological effects of Baihetan Hydropower Station is established to assess Ningnan County by choosing 15 indices. The expert scoring method and the normalized method are employed to determine the weights. The values of various indices are determined according to the statistical yearbooks of Ningnan County from 2009 to 2013 and the related construction planning documents of Baihetan Hydropower Station. Finally, the values of the comprehensive indices for the ecological effects are calculated, and each specific index is analyzed. The results show that the value of the comprehensive index(E)for the ecological effects of the construction of Baihetan Hydropower Station is 0. 1703, and it is in a positive state and but not obvious.