Degree of localization of magnetic moment is becoming an important keyword to understand many exotic phenomena in condensed matter. UPt2Si2 has been long considered as a rare example of uranium intermetallic compound with strongly localized f-electrons. Recent DFT calculation, however, suggests alternative view questioning the degree of localization in this system. Furthermore, high field magnetization and resistivity measurements finds Lifshitz transition driven by the change of Fermi surface. In order to better understand the nature of magnetism in system, it is essential to investigate the new field-induced magnetic phases with direct neutron scattering method at EXED, HZB.