A successful attack against vital maritime infrastructures has the potential to cause major economic disruption and create mass casualties and conflagration at national levels. Taking into considerations the vital importance of the seaports, the vulnerable points in the seaports must be recognized and necessary steps should be implemented in order to prevent potential adversary’s attacks. Therefore, a coordinated pattern is provided in this investigation to identify the vulnerabilities and provide security of the ports, through the identification of the assets and the ongoing threats based on passive defence considerations. In this article, attempts have been made to introduce a critical infrastructures’ vulnerability assessment method which is the product of combined local and current methods such as RAMCAP. This method is based on risk assessment as a function of threat, vulnerability and effects where assets, threats and vulnerabilities are estimated and security measures are implemented. Therefore, Fuzzy method is used to model the vulnerability assessment and the results are presented through MATLAB software.