With the widespread adoption and rapid development of social networks, covert communication technology within social networks has faced new opportunities and challenges, and has gradually become a research hotspot in the field of information security. However, there is currently a scarcity of research on the architecture of covert communication systems within social networks. While social networks offer multi-modal steganographic covers, existing studies have predominantly focused on streaming media covers, neglecting a system architecture adaptable to multiple covers. To address this issue, this paper proposes a novel three-layer architecture for covert communication system based on social networks. This architecture is capable of supporting various steganographic covers, including streaming media, images, and text, providing a more flexible and extensive application scenario for covert communication. Following a functional comparison, the layered system architecture for covert communication within social networks proposed in this paper demonstrates compatibility with a broad range of social network covers and adaptability to diverse steganographic algorithms.