For a long period, Southeast Asian economies have been export-oriented, mostly to Europe and North America. To earn foreign exchanges and speed their economic growth, ASEAN countries have moved to combine foreign and national capital to promote indigenous industrial development and native economic growth. For this purpose, ASEAN countries have set up enormous foreign investment incentives to attract foreign capital and enacted related foreign investment regulations many times to catch more foreign investors’ eyes. However, the dissimilar economic developmental levels and the different political backgrounds, ASEAN countries have varied investment environment and regulations. Since both the formation of ASEAN and ASEAN members themselves are more focused on attracting foreign investment, one may ask what differences of foreign investment environment and regulations ASEAN member states have? The article hopes to analyze ASEAN member’s investment environment and selected members’ investment regulations in order to examine the interactions between national developmental demands and foreign investment regulations through a comparative study of ASEAN member states’ laws on foreign investment.