This study aims to calculate the coefficient of industrial diversification in relation to the number of workers in the industrial sector . The study adopted the " Tress index " for the calculation of industrial diversity as the most obvious indicators in this field and in line with the methodology of the study. The results of the study showed a difference in the degree of industrial diversity in the Egyptian governorates.Four types of industrial diversity were also distinguished between the governorates: the highly industrial diversity pattern, the moderate industrial diversity pattern , the moderate industrial specialization pattern ,the highly specialization pattern. The study recommends encouraging industrial investments in the governorates that fall under the industrial specialization pattern. The importance of industrial diversity is of great importance, with the need to pay attention to the industrial sectors with comparative advantage in Egypt, and to increase the degree of industrial diversification in the governorates of diversity and medium industrial specialization. In addition to the need to adopt the principle of industrial diversification mainly in the formulation of industrial policy in Egypt, both in the short term Long.