In this paper, we use the state-space model to build a time-varying model about the foreign direct investment and economic growth, and then test the relationship between the two variables based on a E-G two-step method, test results are as follows: (1) to consider the changing system, there is a time-varying co-integration relationship between FDI and economic growth (2) the time-varying equilibrium has an downward trend along with system changes or policy fluctuating.