First, based on the data collected, the countries that have ever possessed nuclear weapons are screened, and the nuclear bomb stockpiles of each country in the last 20 years are counted, and the change in the total number of nuclear weapons of each country is found, and the most change in the nuclear weapon stockpile of the United States in 20 years is obtained. Immediately afterwards, the number of nuclear tests by country was added up by year and the five years with the highest number of nuclear tests worldwide were 1962, 1958, 1968, 1966 and 1961. Subsequently, the stockpile of nuclear bombs and the number of nuclear tests were selected as measures of nuclear weapons research activity, and the Topsis model (Technique for Order Preference by Similarity to Ideal Solution) was used to obtain a score for each country to determine the level of activity, with the United States ultimately having the highest level of activity. Finally, the speed of transition from disregard to possession of nuclear weapons is found, and the final ranking gives the country with the fastest transition speed, again giving the fastest transition speed for the USA.