Setting a capacitive filtering device on the passive network can play a role of smoothing AC voltage waveform, supporting AC voltage, etc. In this paper, the positive-sequence and negative-sequence equivalent models of the MMC station which connected to the capacitive filtering device on the passive network, is given by derivation of equation. Then, according to the requirement, the conventional double closed-loop controller containing an inner current loop and an outer voltage loop is adopted. Further, the decoupling control strategy of the MMC station connected to the capacitive filtering device is proposed, through the analysis of the coupling relationship between the d-axis component and q-axis component. Simulation studies are carried out under different operation conditions, such as load change, AC voltage drop, system frequency decline and unbalanced load, through the MMC-HVDC simulation system built in PSCAD/EMTDC. The simulation results indicate that the designed controller can satisfy the requirement of fast control, and has good steady accuracy and transient response characteristics.