According to the new communication network controller area network（CAN） bus and IEC 61850 standard for substation， a new type of status monitoring intelligent electronic device（IED） for circuit breaker which is applied to transformer substation spacer layer is designed. A double CPU structure which contains ARM and digital singnal processor（DSP） chip is the hardware kernel of the IED， and the Linux operating system and C language constitute the software development platform. The circuit breaker IED is embedded with IED capacity description（ICD） documents which meet IEC 61850 standard. The data transmission is carried out through the CAN bus and on-line monitoring devices of circuit breaker（process layer）. Then it communicates with the monitoring center（the station control layer） by optical fiber in accordance with IEC 61850 standard. The synchronous samplings of signals of the opening and closing coil and the energy storage motor are accomplished with IRIG-B code. The practical operation results show that IED can realize the signal collection， analysis， processing and transmission of the circuit breaker on-line monitoring device， the monitoring center personnel can make a long-distance on-line monitoring on the operation state of the circuit breaker in transformer substations.