Abstract: International space law treaties not only vest the states parties to these treaties with the right to peaceful exploration and use of outer space, but also impose on them the international duties of bearing responsibility for their national activities in outer space. But there are greatly differences in standards and practices in respect of implementing these duties, which makes national legislation an important problem. Under the circumstances, ILA has worked on a series of studies on the national legislative practices, based on which five "building blocks" for national legislation have been gradually developed. The five "building blocks" consists of authorization of space activities, supervision of space activities, registration of space objects, compensation regulation and additional regulation. The five "building blocks" theory for national legislation not only plays the important guiding role in the promotion of the harmonization of the European states' national space law governing their space activities, but also is fully applied in the practice of drafting Sofia Guidelines for Model Law on National Space Legislation and endorsed by UNCOPUOS. In addition, the theory has an evolutionary relation with the eight component elements necessary to National Space Legislation proposed by UNGA. The five "building blocks" theory for national legislation and the eight component elements necessary to National Space Legislation proposed by UNGA certainly have meaningful reference to the practice in our national legislation. It is particularly proposed that five "building blocks" or eight component elements for National Space Legislation be taken into consideration to act as the indispensable content or reference standard for the future legislation governing the commercial aerospace activities in China.