During Thailand's Economic Crisis in 1997, the people soon lost their assets and then fell into panic in Bangkok. The King of Thailand brought up an economic thought in a speech at this time point. But many mistakes were made by foreign businessmen. So the King and the government of Thailand had to explain the thinking. As time passed, the explanation step by step let the thought become more clearly and completely understood. At last, these concepts became a core value of theory. This theory is called "Sufficiency Economy." In the first part of this article, we want to understand the core value of the Sufficiency Economy, and its application. In the second part, we want to provide an example to know how wonderful its use is in our life, and try to understand the mistakes of foreign businessmen. In the third part, we try to show how the Sufficiency Economy affects Thai people, especially in society, economy, and culture.