Conversion technique of HVDC has become a dominant technology for long distance bulk power transmission. The AC and DC system are interconnected by HVDC converter thus, it becomes the medium of the harmonic transfer. The presence of harmonic not only increases the losses, but it can also lead the system to collapse. In this study, the passive filter is used to mitigate the harmonics in both the AC and DC sides of the HVDC network by tuning it until satisfied with the harmonic standard. The test system of TNB-EGAT HVDC link is modelled using PSCAD software with AC voltage rating of 275 kV and 230 kV for rectifier and inverter side, respectively. The system is controlled by the control system that has been modelled according to CIGRE Benchmark. Comparison of the simulation results between before and after the implementation of passive filters in the system reveals that the harmonics have been mitigated effectively. The results show that the level of THD current at the AC side reduced to 0.2336% and 0.0154% at rectifier and inverter side, respectively.