It is the future development trend of large-scale onshore or offshore wind farms to be connected to the grid by VSC-HVDC (Voltage-Source-Converter-based High-Voltage Direct-Current Transmission) system. In order to ensure the fault ride-through capability of wind farm and its grid connected system, energy dissipation devices are often installed in the DC system. Before the flexible DC transmission system equipped with DC energy dissipation devices is put into operation, it is necessary to carry out on-site test to check whether the functions of the equipment meet the requirements of operation. However, it is difficult to simulate the real working conditions of energy dissipation devices, that is, to provide suitable and stable DC voltage. Therefore, this paper proposes an on-site test method for DC energy dissipation device, without additional test equipment. After the installation of relevant equipment on field, stable DC voltage is provided through the AC system and the VSC converter, and the relevant parameters of DC energy dissipation device are changed to make it enter the switching process, so as to test its functions on site. The on-site test method is verified on the simulation model of DC energy dissipation devices that is configured in an offshore wind power VSC-HVDC project on the RTDS platform. The impact of different control parameters on the switching transient process is studied, and the optimized scheme to set the relevant parameters is given.