The NEA said the average uptime for projects of 6MW and over across China was 1,905 hours. The decline was largely down to curtailments and weaker wind conditions in the northern provinces of Jilin and Gansu.
However, China's wind capacity rose by around 30% to reach 18.81GW during 2014. Wind has overtaken nuclear energy to become the country's third largest energy source, after coal and hydropower.
The NEA statistics also show grid-connected wind installations totalled 95.81GW by the end of 2014, up 25.6% on the previous year.
In terms of regional output, Hebei, Shanxi, Inner Mongolia, Ningxia and Xinjiang all performed well, with the latter area registering an average uptime of 2,094 hours.
The coastal province of Fujian in southeast China scored the highest figure of 2,530 hours in annual wind power generation.