Hydropower, next to coal, is the second most important source of electric power supply in China. It amounted to 20.4% of the nation's total installed capacity of electricity generation in 2011. To provide a comprehensive picture of the development of hydropower in China and its potential environmental impacts, this study calculates the ecological footprint and greenhouse gas emission reduction of hydropower development in China over the past 60 years. The ecological footprints include the energy ecological footprint and arable land occupation footprint. The energy ecological footprint is calculated in terms of the area of the land which would be used for reforestation in order to assimilate CO₂ emissions from fossil energy consumption for hydropower development. The arable land occupation footprint is calculated in terms of the area of the land to be inundated by hydropower development. The calculated energy ecological footprint was 502 422 ha in 2010 or about 0.3% of total arable land in China and the calculated inundated land was about 1.42×10⁶ ha or about 1.2% of total arable land in China. The regional power grid baseline method was used to calculate the greenhouse gas emission reduction. Results indicated that CO₂ emission reduction from hydropower development was increasing rapidly since 1949 and reached 5.02×10⁸ tons of CO₂ emission in 2010, with an accumulative total of 6.221×10⁹ tons of CO₂ emission during the period 1949–2010.