Ancient archaeological sites contain numerous pottery objects that suffered from different deterioration factors. This study aims to use different analytical methods to study the chemical and mineralogical composition and identification of deterioration aspects of some ancient Egyptian pottery jars from Saqqara excavation. Thus, to explain the deterioration factors' mechanisms and apply the proper conservation methods to the deteriorated pottery jars. AutoCAD, digital microscope, scanning electron microscope (SEM-EDX), and x-ray diffraction (XRD) were used to clarify the preservation states of pottery jars. The results of the investigation revealed that the selected jars suffered from different cracks, salts crystallization, some surface black spots, separation of the slip layer, and heterogeneity in the grains size. XRD analysis revealed that quartz, diopside, illite, muscovite, orthoclase, anorthite, and hematite are the main components of the jars. SEM-EDX analysis showed high concentrations of chlorides and sulfate salts, besides the presence of manganese oxide. Different treatments were performed for the pottery jars include mechanical and chemical cleaning. Additionally, the completion process was done by using a mixture of dental gypsum with grog. Moreover, the consolidation process was achieved by using paraloid B-72.