The legal construction of the great bay area is a guarantee of realizing the economic and financial development goals within this area and the process of legislation could not be broken away from the solid analysis of the legal theory. China's great bay areas are now facing the integrated economic background with the multiple scope of law in the Guangdong-HK-Macao Great Bay Area. When facing with the theoretical debates from different scholars, which are "programmatic legislative theory vs. detailed legislative theory", "top-level legislative theory vs. paralleled legislative theory" and "responsive legislative theory vs. procedural legislative theory", China should use comparative study and fully analyze the legal construction experiences in the bay area from different states before going on the legislative activity. China's great bay areas should adopt the programmatic legislative theory and the responsive legislative theory. Meanwhile, the Guangdong-HK-Macao Great Bay Area should adopt the paralleled legislative theory as a respect to the high degree of autonomy of HK and Macao, and the Zhejiang Great Bay Area is good to use the top-level legislative theory to formulate a uniform legislation.