The invention provides a security gateway based on multi-channel CAN bus and Ethernet communication and a communication method. According to the security gateway and the communication method thereof, multiple Ethernets are used as a backbone network for information transmission, and multiple CAN buses are connected to directly communicate with an in-vehicle controller and in-vehicle testing equipment, such that secure and efficient real-time data communication can be realized. Since the security gateway employs multiple CAN buses and Ethernet links, the communication time is greatly reduced, and the communication efficiency is improved.