The convergence of rules is an important starting point and the core key to the construction of the Guangdong-Hong Kong-Macao Greater Bay Area. However，as Guangdong，Hong Kong and Macao belong to three different legal domains and independent customs territories，they have different legal systems，so there are practical difficulties in the convergence of rules. This report in examining a large bay area of Guangdong in customs clearance services，financial services，business environment，science and technology innovation，legal service and social livelihood of the people in key areas such as rules of cohesion on the basis of the status quo，analysis of the rules of cohesion of the objective existence of problems and difficulties，put in adhere to the principle of “one country，two systems” under the rules of cohesion’s advices. It is necessary to innovate regional development systems and mechanisms to promote the convenient flow of elements in the Bay Area；to innovate the long-term mechanism of the Bay Area platform to promote the integration of business environment rules；to innovate the legal service guarantee mechanism to lay a solid foundation for the implementation of rules integration.