The main objective of IEC 61850 is the interoperability between different vendors' equipments. The acquisition of the basic information model is the precondition for the deep-level interoperability tests of IEC 61850. Based on an analysis of the associates， directory and data definition services in the abstract communication service interface（ACSI）， and initiation and variable listing services in the manufacturing message specification（MMS）， a mapping rule between ACSI and MMS is suggested. An implementing method of the ACSI basic information model acquisition based on MMS is proposed. Furthermore， a prototype system based on the above method has been designed， which includes the ACSI manager， specific communication service mapping（SCSM） manager， MMS protocol machine（MMPM）， ASN.1 encoder/decoder and ACSI/MMS application software. It has passed interoperability and function tests.