Avionics Full Duplex Switched Ethernet (AFDX) is a deterministic network bus for interconnecting avionics systems based on the industry-standard Ethernet communication protocol with adaptive improvements and is currently used on large aircraft such as the Boeing 787 and Airbus 380. The Open System Interconnection (OSI) seven-layer model is a system of standards developed by the International Organization for Standardization for the communication and relationship between multiple systems or devices. This paper summarizes and analyzes the working mechanism of the AFDX bus at a deep level by deeply analyzing the mapping relationship between AFDX and OSI model, starting from the basic principle of data communication, and gives a development example through engineering application, which provides a reference for the design of AFDX bus for domestic civil aircraft.