Abstract: For a long time, nuclear shell structure is an important issue of nuclear physics. In particular, with rapid development of new generation of nuclear radioactive ion beam facilities and detectors, new shell structures appearing in neutron-rich nuclei have largely attracted the interests of the field, including the mechanism behind and the evolutions. Under the frame of relativistic Hartree-Fock theory founded on the meson-exchange diagram of nuclear force, taking calcium isotopes, doubly magic nuclide ²⁰⁸Pb and the selected superheavy and exotic nuclei as examples, this paper reviews the occurrence of new sub-shells in neutron-rich nuclei, the pseudo-spin symmetry (PSS) restoration and the in-medium nuclear attraction-repulsion balance, the PSS restoration/violation and nuclear shell structure, novel phenomena, etc., in which the roles of the Fock terms are intensively discussed.