Abstract: High-vacuum oil refinery systems and process are disclosed in this invention. The systems and process enables to carry out vaporization and distillation of oils under the condition of 1-10.sup.-4 Torr of high vacuum and at the temperature of not higher than 360.degree. C. and thereby removing possibility of thermal cracking while heating to be vaporized and easily produces high quality oil. The vaporized gases are centrifugally separated and liquefied by specific gravity using high-vacuum gas specific gravity centrifugal separators and thereby producing high purity oil of uniform quality. The process also carries out vaporization and distillation of the oil at the temperature of not higher than 360.degree. C. so that the process prevents vaporization of sulfur components of the oil, but simply drains the sulfur components along with the concentrated sludge oil and thereby distilling and desulfurizing the crude or heavy oil at the same time without using expensive conventional desulfurizing process.