The surface properties of so-called coulomb liquids, such as liquid metals and alloys and molten salts, have been studied theoretically by many workers. The progress in such studies, however, is slow and there remains many fundamental unresolved problems, because of the difficulties peculiar to the surface of coulomb liquids such as a difference in the charge density distribution of ions and electrons at a surface. In this study we have carried out the Monte Carlo and the molecular-dynamics simulations on the surface of coulomb liquids and calculated the density profile near the surface, correlation functions, the surface tension and so on, and in particular we try to understand the characteristic features of the microscopic structure of the surface of coulomb liquids. We have obtained some important results from our studies. Particularly, it should be emphasized that we have found a very interesting phenomena of the surface crystarisation by performing the Monte Carlo simulation on the classical one-component plasma. This phenomena is really peculiar to the surface of coulomb liquids. We have also carried out the computer simulations, including the Car-Paffinello method, on bulk liquid metals and molten salts as a preparation for studying the surface properties of these systems.