The cutting tool wear detection of shield has become one of the key technologies of shield tunneling construction; also it is one of the greatest difficulties during shield tunneling construction. In order to realize realtime detection of the wear conditions and wear laws of cutting tool in complex geology, timely cutting tool replacement, reduction of unpurposed shield stop and speeding up construction schedule, a series of shield cutting tool wear detection system is developed based on ultrasonic detection technology and wireless communication technology. The application of the system shows that: 1) The detection results of the system coincide with the monitoring results well, which illustrates that the ultrasonic technology is available for shield cutting tool wear detection. 2) The 433 MHz wireless communication technology is available for online realtime monitoring of shield cutting tool; and it shows high accuracy and reliability. 3) The detection system, has the characteristics of antivibration, antiinterference and waterproof; also it is stable and rational.