A graph processing system may include at least one auxiliary memory configured to store graph data including phase data and attribute data, a main memory configured to store a portion of the graph data, a plurality of graphics processing units (GPUs) configured to process the graph data received from the main memory and perform synchronization and including cores and device memories, and a central processing unit (CPU) configured to manage query processing associated with the graph data performed by the GPUs and store, in the auxiliary memory, updatable attribute data of a result of the query processing.