The invention provides a single-arm folding insertion type +/-1,100kV ultrahigh-voltage direct-current disconnecting switch. The switch comprises basic supports, an electric motor operation mechanism, a moving side triangular base, moving side supporting insulators, an operation insulator, a moving side upper underframe, a main knife switch, an arcing horn, a fixed contact, a static side upper underframe, static side supporting insulators, a static side triangular base, a moving side voltage equalizing shield, toggle voltage equalizing shields and a static side voltage equalizing shield. The moving side voltage equalizing shield is arranged above the moving side upper underframe, the moving side upper underframe and the part, connected with the main knife switch, of the moving side upper underframe are completely wrapped in the moving side voltage equalizing shield, the two toggle voltage equalizing shields symmetrically on two sides are arranged on the connection part of an upper tube and a lower tube of the main knife switch, the arcing horn and the fixed contact are arranged above the static side upper underframe and completely wrapped in the static side voltage equalizing shield, the technical requirement of a +/-1,100kV ultrahigh-voltage direct-current transmission project is met, and the disconnecting switch has the characteristics of being good in insulation performance, stable and reliable in operate and high in current carrying ability.