Abstract: Distributed consistency control has become a new choice for the secondary frequency control of multi-terminal flexible direct current (MTDC) systems because of its flexibility and synergy. Although the distributed control structure improves the frequency modulation capability of the MTDC system, it brings the threat of network attacks. To this end, this paper first studies the adverse effects of the constant false data injection (FDI) attacks on the distributed secondary controllers, and the analysis results show that the FDI-attacked sites persists with the frequency deviations related to the attack vectors. Furthermore, in order to eliminate the frequency deviations caused by the attacks, this paper proposes a distributed consistency control strategy to resist the constant value FDI attacks by using the characteristic that the constant value differential is zero, which theoretically proves that the proposed strategy can eliminate the deviation caused by the FDI attacks. Finally, a four-terminal flexible DC system simulation model is built based on the MATLAB/SIMULINK, and three attack scenarios are simulated, i.e. a single converter station is attacked, all converter stations are attacked at the same time, and all converter stations are attacked at different time periods. The results show that the proposed control strategies can eliminate the impacts of the FDI attacks in the three given scenarios, and make the MTDC system realize the secondary frequency modulation.