The invention provides a communication method and a communication system. The method comprises the steps of building a first communication message between a communication interface of a controller and a steel roil tracking unit, and using the first communication message to acquire steel coil information; and building a second communication message between the communication interface of the controller and steel coil detection equipment, wherein the first communication message also comprise trigger information, and the controller sends the steel coil information to the steel coil detection equipment according to the trigger information; therefore, the controller can communicate with the steel coil tracking unit by using the first communication message, and receive and store the steel coil information automatically sent by the steel coil tracking unit; the controller can communicate with the steel coil detection equipment by using the second communication message, and automatically send the steel coil information to the steel coil detection equipment according to the trigger information in the first communication message, and thus the steel coil detection equipment can detect the quality of the steel coil according to the steel coil information.