Abstract: In this paper，the concept of Gauss theorem of gravitation field is established based on the similarity

between electrostatic field and gravitation field. We have got the equation of Gauss theorem of gravitation field by analogy，

and of which the earth is approximately regarded as a celestial body with spherical symmetry of mass distribution.

According to the density distribution model of the earth，we fit and calculate the pressure in the earth’s interior

by means of the MATHEMATICA software. It provides a new thinking and way to study the pressure in the

Earth’s interior. Finally，we analyze and discussed the error sources in approximate calculations.

Key words: gauss theorem, earth, the density distribution model, gravitational field, the pressure