Through the SMS(Smart Maintenance System, SMS) on-line monitoring for transformer,the condition of Transformer could be obtained immediately by smart phone. The information include Voltage, Current, Loading, Oil temperature, Winding temperature, Gas in the Oil, Core grounding current,Bushing capacitance, tanδ & leakage current. Ambient temperature and Humidity also could be monitor.Maintenance in accordance with the long-term monitoring of transformer operation information.Furthermore, SMS also provides a rough budget for condition base maintenance, making the cost-optimized maintenance.