Abstract: Combining the parameter perturbation method with the wave functions that obeys space change symmetry， the ground state energy ( GSE) of the helium atom is calculated from the second to the twelfth level approximations. It is found that，with the increase of the level，the ground energy and its change decrease，and the absolute error between the calculated GSE and experiments exists small fluctuation. Therefore，the selection of approximate levels is vitally important for the accurate GSE calculation of the atom.

Key words: helium atom, ground state energy, wave function, symmetry