A service method of gas appliances includes: Detecting the gas appliances at the client ends to generate detecting signals. Transmitting the detecting signals to a service end. Identifying which client end the detecting signals come from. Examining the detecting signals to find whether the gas appliance has an abnormal condition; and informing the client end when the abnormal condition is found. After all, the service end may monitor the gas appliances at the client end, and inform the client for repair when the gas appliance has detected an abnormal signal or has damaged parts.