A method and device for decoding video data are disclosed. More specifically, a method of decoding video data may comprise: configuring a block vector candidate list of a current block to which an intra block copy (IBC) prediction mode is applied, the IBC mode referring to another block in a current picture; and generating a prediction sample of the current block based on a block vector included in the block vector candidate list. Configuring the block vector candidate list comprises: configuring the block vector candidate list from a spatial neighboring block to which the IBC prediction mode is applied; and modifying the block vector candidate list based on an history-based motion vector prediction (HVMP) candidate to which the IBC prediction mode is applied when a number of current candidates of the block vector candidate list is smaller than a maximum candidate number.