Abstract: In the increasingly tense situation of international relations, national science and technology security, which is closely related to national security and major interests, has been put on the important agenda. Then, how to evaluate national science and technology security, so as to provide a scientific basis for government decision-making? Some existing papers have studied national science and technology security assessment or technology sovereignty assessment, but they have not fully reflected the influence of foreign countries on national science and technology security, which shows that the relativity of security has been ignored. Therefore, the assessment of national science and technology security should be analyzed from the perspective of comparison between countries, so cluster analysis method is introduced to this study. The primary indicators used in this cluster analysis include frontier technology readiness index, patent technology security index in key fields and comparative advantage index of high-tech products, and they all have their own secondary indicators. Generally speaking, countries with more advanced science and technology and deeper participation in globalization have a greater impact on foreign science and technology security, and are also more seriously affected by the scientific and technological competition between China and the United States. Hence, this study selected 19 countries in the G20, which can represent the world's major countries, as the comparison objects. In this study, the SPSS27 software was used to conduct a statistical analysis of the relevant data of the three indicators in these 19 countries. Then, ANOVA test method was used to determine the minimum number of reliable clusters in the three indicators, and the elbow rule was combined to select the optimal number of clusters. Finally, the results of cluster analysis reveal the state of national science and technology security of each country. Among them, five countries, including China, India, Mexico, South Africa and Turkey, are in the category of less readiness for frontier technology, higher security of patented technologies in key areas, and stronger comparative advantages of high-tech products. The United States alone occupies a category of the best performance in the security of patented technology in key areas and frontier technology readiness, and a middling performance in the comparative advantage of high-tech products. France, Germany, Italy, Japan, South Korea and the United Kingdom are in the category characterized by the strongest comparative advantages of high-tech products, a higher level of frontier technology readiness, and a medium level of patent technology security in key areas. Argentina, Australia, Brazil, Canada, Russia and Saudi Arabia fall into the category of moderate readiness for frontier technology, low security of patented technology in key areas, and the weakest comparative advantage of high-tech products. And Indonesia is the only country in the category of the lowest level of patent technology security in key areas and frontier technology readiness, and relatively weak comparative advantage of high-tech products. The above different states of national science and technology security provide directional guidance for these countries to formulate corresponding policies. For example, the United States needs to improve its comparative advantage in high-tech products, and China desperately needs to improve its readiness for frontier technologies.