The service platform with mass real time data is the place where the time scalar data of power grid are stored centrally in. In order to meet the demand of power grid dispatching automation and measurement automation, a data access scheme for multi-source heterogeneous grid operation is proposed. The scheme uses relational database and real-time database to store data, define the storage standard of scalar measurement data based on the characteristics of data points stored in real-time database, through the configuration service to achieve data access tasks start and stop control and operation status monitoring, the access scheduler is used to schedule the access plug-in to complete the access task, and introduce the main and standby redundancy technology to ensure the high availability of the scheduler. The concept of component programming is introduced, and the access requirements of multi-source heterogeneous data are met by pluggable and expandable plug-in design. The scheme has been applied in the construction project of massive quasi real time data service platform of China Southern Power Grid Company. It can well meet the demand of China Southern Power Grid operating scalar measurement data access needs.