The regional unified electricity spot market plays an important role in promoting the optimized allocation of power resources in a wider range and promoting the cross-regional consumption of renewable energy. Based on the Southern China Regional Electricity Market, building a unified electricity spot market in the Guangdong-Hong Kong-Macao Greater Bay Area will play an important role in optimizing the power structure of Hong Kong and Macau, reducing electricity costs in the Greater Bay Area, and improving the reliability of Hong Kong and Macau power system operations. However, there are huge differences in the economic, legal, and administrative systems of the Greater Bay Area, which determines that current power resources cannot completely flow freely in the Greater Bay Area. It is quite difficult to directly build a unified electricity market in the Greater Bay Area. This paper takes the unified electricity spot market as the research object. Firstly, it compares and analyzes the characteristics of typical foreign regional market models and the adaptability to the Greater Bay Area spot market. Secondly, based on the status quo of the Greater Bay Area, the market model and construction path of the unified electricity spot market in the Greater Bay Area are proposed, and a mathematical model and solution of market clearing in the initial stage, decentralized coordination stage, and unified stage are proposed.