Security and justice are the most basic human needs in life. Therefore, the establishment of security and justice was the first concern of the rulers and it has always been the motto of many governments. And it is also one of the most prominent indicators of progress and civilization. Any land that does not include the two key elements of security and justice will never achieve a stable and lasting civilization. These two principles have a special place in the government of Hazrat Mahdi (a.s.) who has the promise of a global civilization based on the revelation teachings, so that this point is also mentioned in many narrations issued about the advent of Hazrat Wali Asr (a.s.) has been It is for this reason that the phrase "Fill the earth fairly and fairly" is a familiar phrase for someone who has the least amount of study in the field of Mahdavi teachings.  In this article, the role of security and justice in the establishment of the Mahdavi civilization has been discussed with the benefit of the words of Masooman. The solid result of which was the serious role of these two in the formation and continuation of that great Islamic civilization.