Using the method of elastic scattering between a light nucleus and a heavy nucleus at energies below the Coulomb barrier, we try to precisely and systematically determine the electric polarizabilities of 3He and 4He. The precision of R(E) (see Eq. (1)) in our experiment is about 0.1% and thus this experiment is very challenging. In order to reach this precision, some studies about systematic uncertainties are conducted, such as a comparison between the methods for extracting the polarizabilities and a calculation about systematic uncertainties due to the misalignment of beam and detector systems. Our results show that the systematic uncertainties are all much less than 0.1% and are therefore negligible. Detailed data analysis is still in progress.