Expectation on national feature economic scales of a country is essential not only for establishing and evaluation of a middle and long-term fiscal plan but also for planning and evaluation of pension reform and long-term social welfare policies. Production Function approach generally used to long-term expectation of GDP has a weak point that it often uses unrealistic hypotheses or substitute variables to estimate capital stock and total factor productivity.

This research excludes unnecessary hypotheses and avoids using defective data by estimating expectation of long-term GDP through Auto-regressive model with non-linear deterministic term. As results, GDP growth rate will decrease by 4.09% in 2013, by 3.01% in 2013 and reach 2.35% in 2050. However GDP growth rate will more sharply decline when aging population is taken into consideration reaching 0.66% in 2050. In this case, GDP per producing population and the number of producing population should be calculated respectively and multiplied each other.

To summarize the main points of this research, the government should slacken off the decline of producing population through encouraging childbirth policies in order to prevent a sharp drop in GDP growth rate. At the same time, the government should complement quantitative decrease of producing population with rise in productivity and improvement of human capital in quality in the long-term.