Abstract: The CMS protocol is a domestically autonomous and controllable communication protocol formulated by the State Grid Corporation of China based on the DL/T860 standard, It is used to replace the original MMS protocol and represents a domestically implementation of the IEC61850 standard at the station control level, Compared with the MMS protocol, it is more secure and efficient. This article considers adding APER encoding and decoding on the basis of the open-source library libIEC61850 to implement CMS services, based on libIEC61850 for modeling and communication, and using asn1c for APER encoding and decoding. On the foundation of the libIEC61850 framework, CMS protocol handling is added, This method can quickly and efficiently implement CMS services while maintaining compatibility with the MMS protocol.