Abstract: This paper proposed a new multi-infeed interaction factor calculation method considering the small disturbance response characteristics of HVDCs. Firstly, it was theoretically derived that under small disturbance conditions, the dynamic characteristics of HVDCs can be equivalent to an additional admittance matrix. Then, according to the HVDC steady-state equations, the formulas for calculating the elements in the matrix were derived under four different HVDC control modes. Finally, the additional admittance matrix was used to correct the node admittance matrix of the AC system to get the corrected node impedance matrix, and then the multi-infeed interaction factor can be obtained by calculating the impedance ratio. The method can accurately consider the dynamic response characteristics of HVDCs, and can also effectively consider the dynamic（impedance） characteristics of components such as sources and loads. The simulation and calculation based on the example of dual-infeed HVDC system proves the accuracy and effectiveness of the proposed method. In addition, the influence of different HVDC control modes on multi-infeed interaction was also analyzed.