The embodiment of the invention discloses an early warning method and an early warning device for an electric-thermal coupling system. The method comprises the following steps that: obtaining the dataof an electric-thermal coupling system component, and determining the initial operation state of a system; simulating component faults in the electric-thermal coupling system in sequence, updating the data of the system, and adopting an optimal model to determine a load removal amount caused by a current fault for the system; and judging whether the load removal amount exceeds a system load removal amount threshold value or not, and when the load removal amount exceeds the threshold value, giving an early warning signal. The device is independently connected with the electric-thermal couplingsystem and a dispatching mechanism. On the basis of the current operation state of the system, the influence of an expected fault on the electric-thermal coupling system is simulated, the early warning signal is provided for the dispatching mechanism, and fault influence anticipation can be accurately and effectively carried out. A regulation and control mechanism can put forward a response planby aiming at the fault, and severe damage caused after draft faults practically appear can be avoided.