This study analyzes and synthesizes international experiences in allocating greenhouse gas emission quotas, drawing lessons for Viet Nam's developing carbon market. The research examines emission trading systems (ETS) and quota allocation methods from various countries and regions, including the European Union, Germany, Austria, the United Kingdom, Switzerland, the United States, Canada, Nigeria, Kenya, South Africa, China, Japan, and New Zealand. Key findings highlight the importance of diversifying allocation methods, combining free allocation, auctioning, and benchmarking approaches. The study emphasizes the need for flexibility in system design, adapting to specific economic and social conditions of each country. Lessons learned include prioritizing high-emission reduction potential sectors, setting reasonable emission caps based on actual data, ensuring transparency in information disclosure, and establishing effective monitoring and evaluation mechanisms. The research also stresses the importance of providing technical support to businesses, especially small and medium enterprises, in complying with ETS regulations. Additionally, the study addresses concerns such as preventing carbon leakage, assessing social impacts, and ensuring international compatibility of the system. These insights provide a valuable foundation for Viet Nam to develop an effective greenhouse gas ETS that aligns with national conditions and sustainable development goals.