A method for improving data storage security, applied in a cloud storage system comprising a management server and a storage server, comprising: allocating, by the management server, a storage space for a cloud storage resource pool according to attribute information of the cloud storage resource pool; encoding, by the storage server, user data sets in the cloud storage resource pool with an erasure coding algorithm of a first security level N+M, to obtain encoded user data sets; detecting, by the management server, access counts of the encoded user data sets in the cloud storage resource pool; determining, by the management server, from the encoded user data sets, a first user data set whose access count in the cloud storage resource pool meets a preset condition; obtaining, by the management server, a second security level N+(M+i) according to the attribute information of the cloud storage resource pool, wherein the attribute information includes the first security level having a security step M and includes an increment i for the security step, wherein N is a number of nodes for a user data set in the cloud storage resource pool, M and M+i are maximum numbers of abnormal nodes in the nodes for the user data set in the cloud storage resource pool, which when the number of damaged nodes is less than or equal to M or M+i, the user data set can still be read otherwise the user data cannot be read, M, N, and i are integers greater than 0, and M+i is less than or equal to N, and the second security level has a security step greater than that of the first security level; and re-encoding, by the storage server, the first user data set with an erasure coding algorithm of the second security level to obtain a re-encoded first user data set. allocating, by the management server, a storage space for a cloud storage resource pool according to attribute information of the cloud storage resource pool; encoding, by the storage server, user data sets in the cloud storage resource pool with an erasure coding algorithm of a first security level N+M, to obtain encoded user data sets; detecting, by the management server, access counts of the encoded user data sets in the cloud storage resource pool; determining, by the management server, from the encoded user data sets, a first user data set whose access count in the cloud storage resource pool meets a preset condition; obtaining, by the management server, a second security level N+(M+i) according to the attribute information of the cloud storage resource pool, wherein the attribute information includes the first security level having a security step M and includes an increment i for the security step, wherein N is a number of nodes for a user data set in the cloud storage resource pool, M and M+i are maximum numbers of abnormal nodes in the nodes for the user data set in the cloud storage resource pool, which when the number of damaged nodes is less than or equal to M or M+i, the user data set can still be read otherwise the user data cannot be read, M, N, and i are integers greater than 0, and M+i is less than or equal to N, and the second security level has a security step greater than that of the first security level; and re-encoding, by the storage server, the first user data set with an erasure coding algorithm of the second security level to obtain a re-encoded first user data set. <EOS>