Starting from the research phase in which different technology regarding petroleum refinery plant which includes three main processes that are upstream, midstream, and downstream and oil extraction processes in brief and different unit operations and processes in detail, characterization of crude oil and various parameters involved in the designing of distillation column was explored. Then comes the designing part which includes the distillation column layout i.e tray, column diameter, number of stages, etc and various methods for designing crude distillation unit i.e McCabe Thiele method, Fenske-underwood-gilliland method, and all other equipments required in a refinery. And the most delightful part is simulation in which aspen hysys software was used for designing the crude oil under provided conditions , after appropriate preheating, ADU unit simulation was performed with the required side strippers and pumparounds and then VDU unit simulation was carried out to maximize the valuable products after ADU unit