The purpose of implementing passive defense projects is to reduce the vulnerability of the country's vital, sensitive, and important facilities and equipment under critical conditions caused by man-made threats. Vital infrastructures are part of the main foundations of industrial areas, and their damage affects the region more extensively. Considering that a significant proportion of the country's gas supply is the responsibility of the South Pars region and that the vital infrastructures of the region are among the attractive focal points for enemy aggression. The present research is among applied research (developmental type), and in this path, library methods, questionnaires (quantitative) were used to collect data, and the research method is analytical-evaluative (survey - case study). To determine the sample size using Cochran's formula, 48 individuals were selected as a sample, and the proposed model of the Federal Emergency Management Agency (FEMA) was used for risk analysis. The results show that, in terms of asset importance, oil and gas facilities with 8.86, communication infrastructure with 8.64, power facilities with 6.71, and water and wastewater facilities with 6.45 have the highest values. Also, twelve evaluated threats were considered, among which the probability of occurrence of air and missile attacks with 9.21, chemical-microbial and nuclear attacks with 9.17, and biological threats with 8.72 have the highest probability of occurrence. The highest vulnerability and risk of communication infrastructure against electromagnetic bombs are respectively 9.114 and 688.47, power facilities against electromagnetic and graphite bombs are respectively 8.446 and 407.47, oil and gas facilities against bombing threats are respectively 8.484 and 655.46, and water and wastewater facilities against cyber terrorism and biological threats are respectively 8.3 and 466.82, and finally, solutions to reduce vulnerability and risk are stated.