The invention relates to the technical field of computers, in particular to a method and a system for encryption-decryption and security management for a file. The method comprises the following steps that: a server loads easy security file encryption management software; a client host loads client proxy software; the server encrypts and saves a file on the client host to a client host hard disc through the easy security file encryption management software and the client proxy software; the client host uploads the file to the server needing the file through the easy security file encryption management software; and the server decrypts the file according to the easy security file encryption management software and generates a circulating file from the file or applies for performing off-line operation on the file. In the method and the system, all files can be encrypted for saving through the professional file knowledge and the protection management platform of the easy security file encryption management software, so that a set of complete and powerful solution is provided for the file management of enterprises.