In this paper, the ab initio quantum mechanics method is used for further investigating the He-N2 interactional potential energy function. By means of different methods and basis sets, the energy data in space are calculated. Finally the accurate He-N2 interactional potential energy function is obtained by using QCISD(T)/6-311++G(3df, 2pd) with Boy and Bernardi's Full Couterpoise to eliminate the basis set superposition error. The calculated differential cross sections of He-N2 collision are in good agreement with the experimental data. The rules of differential cross sections of He-N2 collision at different collision energies are derived.