Abstract: The method of redundancy was general be used to ensure the integrity and availability of data in cloud storage.This paper introduced a distributed coding arithmetic after analyzing those method existing.In the new arithmetic,the operation of coding and decoding was doing in the storage nodes,avoiding coding and decoding for the whole data file simultaneous.Through making full advantage of distributed system,the velocity of data storage was heighten consumedly,the availability of data was also improved,the performance of the storage system was enhanced.