Abstract: In this paper, the development of intelligent sensing technology for key parts of transmission system was reviewed, including vibration and lubrication condition monitoring, and ultrasonic communication technology across the closed metal box. The results show that, vibration monitoring is mainly realized by embedded micro-acceleration sensor and wireless communication technology; Lubrication contact states include pressure, temperature distribution and oil film thickness. The measurement of contact pressure and temperature distribution can be achieved by the metal film resistor sensor, and the oil film thickness monitoring can be achieved by contact capacitance method or non-contact ultrasonic method. Since the closed metal box can shield the electromagnetic signal, it is urgent to realize the bidirectional communication across the box based on mechanical wave. Meanwhile, the research and development of gear vibration and strain wireless monitoring system was briefly introduced. The experimental results show that the recorded internal signal can clearly reflect the speed and contact information, so as to reflect the real-time running state of the transmission system.