On the basis of growth accounting equation, we estimate the natural growth rate of output in the period from 1978 to 2009, and predict it in periods of the 12th FYP and 13th FYP. We find the natural growth rate of output will decline to 7.8 percent in 2011-2015 and to 6.3 percent in 2016-2020. Improving the labor force participation rate will become an important way to increase the natural growth rate of output because China's working-age population begins to decline. And China's potential growth rate of employment will be negative in the 13th FYP. On the basis of the model, we find that the 1% increase of the labor force participation rate will create 0.9% increase of natural growth rate of output. <<