The system of inheritance of Tang and Song Dynasties and ancient Rome has the same characteristics as legal privilege, social rank, patriarchal power and sacrificial rites. The theoretical difference between the inheritance system in Tang and Song Dynasties and the succession system in ancient Rome is “harmony between nature and man,” and the natural law. The inheritance system in Tang and Song Dynasties takes ethical law and patriarchal law as the core, pays attention to the ethical and ethical human feelings and patriarchal order, and the focus of inheritance is basically unchanged, always “from identity to identity.” The inheritance system in ancient Rome, with its focus having changed from identity to property, took rational natural law and religion as its core and conformed to the natural law and the order of blood relationship.