Abstract: In order to suppress high frequency resonance, low-pass filter-based voltage feedforward controllers are commonly used in MMC-HVDC projects. Voltage feedforward control may have negative impacts on MMC-HVDC integrated system stability. Therefore, it is worth analyzing the impacts of feedforward control on impedance characteristic as well as integrated system stability. First, the multi-harmonic linearization method is adopted to establish the MMC-HVDC sequence impedance model considering voltage feedforward control. Then, the impedance sensitivity analysis method is used to quantify the impacts of different controllers on the stability of integrated system. Voltage feedforward control is essential in integrated systems stability analysis and in system stability improvement. Finally, an optimization method for MMC-HVDC impedance control based on voltage feedforward control is proposed to improve the stability of integrated system. The accuracy of the sequence impedance model and the effectiveness of impedance optimization method proposed in this paper are verified in Matlab/Simulink.