The invention relates to an indoor direct current earthing switch comprising a housing and a connecting terminal, an electric control module, a signal output module, an operating mechanism, a manual operation module, an electric operation module and static/moving contacts in the housing; the inner cavity of the housing is divided into front and rear cavities by a vertical plate; the static and moving contacts are installed in the rear cavity, the static and moving contacts are divided into four copper bars which are arranged symmetrically in upper and lower rows and protrude from the rear wallof the housing, one of the two copper bars in the upper row is connected to the negative pole of a direct current power supply system and the other is earthed PE, the two copper bars in the lower roware provided with a mechanical connection joint motion and are also electrically connected through a phase-to-phase short-circuit copper bar; in the front cavity, a wiring terminal block module is mounted on the top, the electrical control module and the signal output module are arranged in the middle in parallel, and the operating mechanism, the manual operation module and the electric operationmodule are arranged below; the operating mechanism module is used for controlling the two moving contacts and also is connected with the manual operation module, the electric operation module, the signal output module and the electric control module, respectively, and the electric operation module is also connected with the wiring terminal module. The indoor direct current earthing switch in theinvention is closed, compact in structure, small in size and reliable in performance.