A data processing system may include: a host including a command queue including a plurality of command storage areas, and configured to store summary information of a second command among a plurality of commands in a reserved storage area of a command storage area, among the plurality of command storage areas, in which a first command among the plurality of commands being a previous command to the second command is stored, when inserting the second command into the command queue; and a data storage device configured to fetch the first command from the command queue and store the fetched first command, according to a new command notification received from the host.