The configuration and engineering calculation of DC transfer switch are analyzed by considering the characteristics of ‘multi-terminal’ and ‘hybrid’ of multi-terminal UHVDC system. Aiming at the problem of complex distributional relationship caused by “multi-terminal” characteristics, a new transfer current calculation method of metallic return transfer breaker (MRTB) and earth return transfer breaker (ERTB), which avoids complex mathematical calculations by combining the random number theory and simulation modeling, is mentioned. The obtained approximate conversion current maximum value can be applied to the configuration of engineering switch oscillating circuit and arrester parameters. Aiming at the "hybrid" characteristics, neutral bus switch (NBS) is not suggested installing into the MMC converter station, its original protection function can be replaced by blocking MMC converter or expanding the protection scope of neutral bus differential protection. The conclusion is verified through simulation models.