Abstract: Based on the models of J.Bloxham A.Jackson(BJ) and the International Geomagnetic Reference Field(IGRF),the distribution of geomagnetic field and its secular variation going back to 1690 year are calculated and analyzed theoretically.The results show that the changing tendencies of the total energy of the two models are basically coincident during the same periods in recent 300 years,the total energy of geomagnetic field is kept decreasing both beyond the Earth’s core and the surface,however,the energy decreasing speed beyond the ground is 2.5 times quicker than that beyond the core.The geomagnetic field energy changes with degrees n,of which the changing relationship shows that the energy changes with degrees n=1-8 every year are relatively stable.The geomagnetic energy density is not well-distributed in the earth’s interior.