Abstract: The geomagnetic field drift is not isolated, and closely related to the generating mechanism of the Earth, and it is a component of the Earth generating mechanism. Based on the principle of power generation for the earth charges and the Earth rotation, the shift of geomagnetic field has been analyzed. The geomagnetic field shift has been explored for the physical quantities relevance and effects to the microcosm and macrocosm of the charge moving of the Earth.The findings further illustrates the systematic composition and the operation mechanism of the Earth's electromagnetic field.The Earth generating mechanism consisting of the Earth rotation,Earth charges,Earth current,magnetic field,Earth electric field,ground electromagnetic current and space elctric field and its orthotomicsystem are structared.The physical significance of the geomagnetic field shift and Westwards shift has been discussed.