Massive renewable energy is connected to the power grid though the grid-following(GFL) converter. The DC-link voltage fluctuates easily when experiencing the challenges, such as grid voltage disturbances, load fluctuation. However, many studies ignore the influence of the DC-link voltage dynamics on the GFL converter. In this paper, the dynamic active current caused by the DC-link voltage dynamics is analyzed for the transient stability of the GFL converter. The dynamic active current would introduce an extra negative damping term in the phase-locked loop(PLL). The estimated domain of attraction(DOA) is obtained though energy function and Lyapunov direct method. Finally, simulation results and experimental results verify the effectiveness of the theoretical analysis.