Abstract: The 4.5 MV electrostatic accelerator of Peking University was designed and constructed independently by China in 1980 s. By this accelerator, in which some beam lines and terminals are installed, the isotope ions of hydrogen or helium can be produced in the energy range of 0.7~3.8 MeV, and continuous or pulsed quasi-monoenergetic neutron fields can be generated by ion beam bombarding target. This facility has provided an open experimental platform for domestic and oversea nuclear technology research groups for many years. In recent years, in order to meet the demand of material research in the fields of energy, aerospace and national defense in China, some upgrading works have been achieved. On the one hand, quasi-monoenergetic neutron fields (<7 MeV, 14~19 MeV) generated by this facility have applied to cross section measurement of (n, α) nuclear reaction and fusion neutron spectrometer calibration. On the other hand, the temperature controlling irradiation, nuclear reaction analysis and other experimental terminals have been installed to develop the function on nuclear materials irradiation damage, quantitative analysis of fusion materials, and so on. In addition, an in situ irradiation terminal for testing the electrical properties of semiconductor materials and an integrated ion beam analysis experimental terminal for studying the distribution of elements at the micro scale are designed. At present, the new terminals have been designed and assembled, and the installation and testing work are in process.