Common data is become more meaningful after dealing with, so it makes hacker get the private information, after dealing with the data, more easier. To the Sensitive Data, the data must be encrypted before outsourced, through encryption to protect user's and company's privacy, but the encrypted data can't be searched over traditional search scheme. In this paper, we solve the problem of privacy-preserving multi-keyword ranked search over encrypted data in big data, called BDES. It can feedback the best search result to users. BDES can solve the problem of traditional Search, such as, inefficient, lack privacy protection, single keyword, multi-users and so on.