The embodiments of the invention disclose secure mail client local data storage and identification methods and devices. The storage method comprises the following steps of: acquiring local storage information of a mail client and hardware information of local equipment of the mail client; encrypting a plain text of the local storage information by taking the hardware information as a key, and generating a local storage information cipher text; and storing the local storage information cipher text into the local equipment of the mail client. Correspondingly, the identification method comprises the following steps of: reading the local storage information cipher text from the local equipment of the mail client; acquiring the hardware information of the local equipment of the mail client; and decrypting the local storage information cipher text by taking the hardware information as the key, and generating the plain text of the local storage information. According to the embodiments of the invention, the security of the local storage information of the mail client can be improved.