Understanding the security environment, as one of the issues of security geography, has attracted the attention of scientific and political circles. Since the main topic of geo-security, i.e. reviewing and studying the international relations and links among the security factors of environment on the local, national, regional and global scale, has a close similarity to the subjects being studied in the national security, particularly at national, regional and international levels. This has resulted in ambiguity regarding the essential reason of the two sciences of national security and geography and their relation with each other and the common and specific concepts and issues of these two among the students and researchers. The main question of the present paper is as follows: ""what is the main reason for the similarity between geography and national security?"" In addition to this question, there are other questions including:
A- What is the relation among geography, national security and geopolitics?
B- What are their specific and common concepts?
C- What are the methodological similarities and differences between these two sciences?
In the present paper, efforts have been made to answer the given questions through comparative method. Based on the achieved results, the main reason for the similarity between geography and national security is studying the key concept of country and government in both sciences. Among the present discussions in the protection geography of national security, the study of relations among the political units is more similar to the study of security. In terms of methodology, the concepts of ""scale"" and ""analysis level"" have the pivotal role in classifying the information, limitation and the range of variables. In terms of ideological schools and methodology, there are also some interesting similarities and differences among the two sciences which will be discussed in this paper
