The invention provides a configuration system and method of a DC switch field in a flexible DC power transmission system. The configuration system comprises a first converter station, a second converter station, a pole-I DC power wire, an additional metal loop and a pole-II DC pole wire. The first converter station is connected with the second converter station through the pole-I DC pole wire, the additional metal loop and the pole-II DC pole wire. The DC switch field is configured under different operation conditions by use of the configuration method. According to the invention, application of a special-purpose earth electrode apparatus is avoided, and application of a DC breaker is also reduced; the operation flexibility of a symmetrical bipolar flexible DC power transmission system is improved, and the possibility that the DC system has to reduce its power is reduced; the operation flexibility and the utilization rate of the symmetrical bipolar flexible DC power transmission system are improved; and the configuration system and method of the DC switch field in the flexible DC power transmission system basically eliminate the DC bias problem and are suitable for short-distance cross-sea power transmission.