Among the three borderline Mainland Southeast Asian countries, located in the Indochinese Peninsula, Vietnam has the best economic performance, compared to Laos and Cambodia. The GDP per capita of Vietnam reached US$4,163 in 2022, which was two times higher than Laos and Cambodia. While economic reform policies, political and economic institutions, and colonial history, are similar in all three countries, why does Vietnam have better economic development? Researchers pointed out the economic factors, specifically the positive effects of economic reforms on economic performance. Nonetheless, it is not convincing, while the economic reform in all three countries emphasized property rights, and encouraged decentralization, privatization, and marketization. This study suggested the religious factor of Confucianism in Vietnam that reinforce the effects of economic institutions on economic development, which leads to greater economic performance. The Confucian characteristics of emphasis on saving, education, and following the government's instruction and policies, support the government’s economic reform, which is conducive to economic development.