Unlike the decades of 1360 and 1370 AH, the population of Iran at the time of writing this article (1403) is experiencing the period of transition to old age and this process continues. Since one of the components of the social power and ultimately the military power of any country is the youth of its population, this research aims to show "how to change Iran's demographic transition towards youth by learning from the experience of the holy defense". Since most of the military and civilian forces, as well as war martyrs and young people, are between 16 and 35 years old, and considering the current trend of Iran's population transitioning to old age due to population policies after the war, this research is based on documentary methods and qualitative data analysis, specifically And this case seeks to know the ways to improve the military power of the Islamic Republic of Iran through the youth of the population. The results of the conducted studies indicate that the number of women in the population pyramid of Iran is higher than that of men, and it makes it necessary to pay special attention to the role of this segment of the society in macro-population policies. The adoption of any strategy that leads to a quantitative and qualitative increase in the population in the territorial geography of the IR of Iran is directly effective on the military power, and the experience of holy defense is a guide for the decision makers in this field.