According to IEC 61850， network based switch operation needs an appropriate interlocking mechanism to implement safe related functions. Compared with the conventional switching order and cyber-interlocking devices used in China， on-line interlocking has higher reliability and real-time efficiency， but the difficulty is that the computing and storage resources in IED are too limited to quickly and accurately calculate the interlocking results when fairly high real-time is required. In this paper， the information and communication structures of the CILO logical node are modeled based on IEC 61850. The method of obtaining the switch gear status， the generation of the interlocking command and distributed operation of interlocking control are analyzed. An implementing mode of on-line interlocking integrated with access control is proposed. The switching order rules are introduced into the extended term of PMI attribute certificate via the custom-made interface. The configuration of interlocking rules can be made while acquiring the access privilege at the same time. An analysis of an example of operation and real-time character shows that this method can meet the requirements on the specified functions.