Abstract: By using the Hylleraas-type wave function, the expression for the energy of Helium in the ground state is derived in detail. The variational minimum of ground state energy is obtained by the help of Mathematica. The theoretical value of energy is in agreement with experimental data, and the relative error is less than 0.04‰.This calculation is easy to understand, thus it is very suitable for the teaching purpose.

Key words: Helium, ground state, Hylleraas method, Mathematica