On the basis of analyzing metadata standard specifications of major open data, we integrate the open data described by various metadata standard specifications and construct the field mapping table of core metadata of open data, providing a solution for the cross-platform sharing of open data. The index fields needed for metadata mapping are extracted, and the mapping data are in the formats of JSON and XML, respectively. Through the metadata mapping, the open data described by different metadata standard specifications are incorporated into the same framework. The mapping mechanism in this paper can effectively realize the interconnection of open data resources on different platforms and enhance the sharing of open data.