If your company is Thai majority owned, you can do almost any kind of legal business. However, if yours is a foreign majority owned company, set up inside or outside of Thailand, you can do business with the following conditions:
(1) Non-restricted Businesses
General rules are that if your foreign majority company does export (from Thailand) or manufacturing businesses, it can operate the business without having to apply for a Foreign Business License.
(2) Restricted Businesses
Nearly all types of service and retail businesses are restricted to foreigners. As a foreign majority company you may obtain exemptions through getting a Foreign Business License or a Board of Investments (BOI) promotion, or in case of US companies or American majority companies, registration under the Treaty of Amity and Economic Relations between the United States of America and the Kingdom of Thailand. It should be noted that for some types of businesses, exemptions cannot be obtained.
Click for more information of Thailand Foreign Business Law or for the full version: https://msnagroup.com/thailand-business-company/thailand-foreign-business-law.