Construction of smart city has become a historical trend in the world. The management of underground pipes and the intelligent concrete are the main part of building smart city in China. Compared with the available electronic marker system, SAW-RFID system has shown excellent properties: truly passive, strong penetrating capability, long service-life, sensing and ID integration, and etc. Thus, SAW-RFID system is particularly applicable and has excellent application prospects. However, in practical implementation, the limitation of detection depth has become an obstacle on the application of SAW-RFID for the smart city in the future. Some methods to enhance penetration depth further are proposed.