Directory and data definition services are important for IEC 61850， but these functions cannot be directly realized by manufacturing message specification（MMS）. Other methods must be adopted to help resolve the problem. Directory and data definition services for IEC 61850 are analyzed as are the corresponding MMS services. Several possible implementation methods are presented with their advantages and disadvantages compared. By taking the definition of the named variable in MMS into account， a realization method is proposed， in which both the function accuracy and running efficiency are considered.