This paper introduces a safety earthing device-copper plate-rope of copper wires connected by silver joints. The device is used for earth ground of GC-MS-DS. It is to be buried in the ground 2.5m deep and improves the surrounding soil of salt quantity by MC-07 galvonometer (made in U.S.S.R). The average value is 2.3Ω<4Ω. The measure principles are also discussed.