Disclosed is an RAID5 (redundant array of independent disk 5) write IO optimization processing method. The method includes following steps: 1), storage system creation; 2), data reading and writing operation; and 3), failure data block recovery and has the advantage of capability of effectively lowering write amplification effect of RAID level disk arrays. For conventional magnetic disks, sequential write performance is much higher than random write performance. The address mapping method enables random write operation to be converted into sequential write operation, write performance of the magnetic disk is effectively brought into play, IO operation needed for computation checking is lowered, and response capability of an RAID system is evidently improved, and power consumption of the system is lowered. In addition, an address mapping module can flexibly choose arrangement positions and the number of checking blocks, so that the RAID5 write IO optimization processing method is not limited to be applicable to disk arrays of RAID5 level and can be popularized for realization of RAID4 and RAID6 levels.