The invention discloses an RAID (Redundant Array of Independent Disks) based data reading and writing method and a system thereof. The method comprises the following steps of: during carrying out reading/writing operations on data subblocks in the RAID, if reading/writing failures occur, recording data subblocks with resding/writing failures to an off-line data subblock list; and when the reading/writing operations are needed to be carried out on the RAID, if the information of a target data subblock of the current reading/writing operation is queried in the off-line data subblock list, carrying out the current reading/writing operation by using other data subblocks and verification subblocks in a strip to which the target data subblock belongs. The invention can improve the reading/writing property of the RAID.