As the oil prices keep increasing, the need for energy conservation becomes a real necessity in oil refinery plant especially in crude oil distillation unit in order to reduce both the operating cost and gases emissions. The important method that used for energy saving is the optimization of heat exchanger network (HEN) design, which can be applied using various methods. In this study, Pinch Technology (PT) is applied using real data, in order to obtain optimum energy savings in preheat exchanger network of the crude oil distillation unit at Zawia Oil Refining Plant. Applying such technique has shown how to save considerable energy during the heat exchanger network design. From the HINT results the optimal value of ΔTmin found to be equal to 20C, and the pinch point was found to be 116 C. It has been also found that 23831.5 KW minimum heat flow must be supplied from hot utilities and 10882.8 KW minimum heat flow must be removed by cold utilities. The operating cost for both hot and cold utilities was estimated to be2.97*106 $/year. Furthermore the estimated total heat transfer area was found to be 14507.48 m2 and the predicted annual capital cost was equal to 8.7*105$/year. The obtained results are considered to be extremely promising for achieving considerable improvement in energy savings for the investigating unit particularly when retrofit design will be applied in the following part of this work