Shell-model calculations of sd-shell nuclei, F. Xu, Peking University, China − Nuclei at the limit of existence are attracting much interest.  Particularly interesting are the sd-shell nuclei in which many new experimental data have been available recently.  At the limit of existence, many novel properties, such as new shell closures and anomalous electromagnetic transitions, have been observed. These are challenging quantitative descriptions of theoretical models, and also providing a good playground for the study of nuclear force.  We have performed shell-model calculations with different kinds of NN interactions, investigating the structures of the sd-shell nuclei in both neutron-rich and proton-rich regions.  The calculated properties of mirror nuclei are compared to study the isospin dependence of nuclear force in the sd shell.  By analyzing the components of various configurations in the wavefuctions of the studied states, it is found that configuration mixing plays an important role in the shell evolution in the drip-line region. We have also calculated the quadrupole electromagnetic transitions of excited states.  Calculations are quite sensitive to effective charges used.  The shell-model calculations have been compared systematically with available data, giving useful understanding of structures of the sd-shell nuclei at the limits of existence.