Abstract: In order to solve the problem of high keywords-search time-complexity caused by excessive security indexes in symmetric searchable encryption scheme， combined with the cloud storage application environment， a new searchable encryption (SE) scheme for encrypted large data sets in distributed environments was presented. The scheme was aimed at data owners who have large sizes of files in the cloud storage application environment. By using block storage structure to optimize the structure of security index， the security indexes were divided into three categories: Small， Medium， and Large， according to the block parameters. And with the method of register indirect addressing， the scheme can maintain good search time complexity in the case of large security index， and be acceptable for users. The experimental result shows that the keyword search time reaches sublinearity as the security index increases.

Key words: searchable encryption, inverted index, cloud storage, file encryption, large data sets