The invention is suitable for the field of data security and provides a method and device for enhancing data security. The method comprises the following steps of: during data writing, creating a data storage and randomly generating a key of the data storage; encrypting written data with the key of the data storage by using an encryption algorithm provided by a coder-decoder to generate a cipher text, and storing the key and the cipher text in the data storage; updating the key stored in the data storage by adopting a preset key updating strategy; and during data reading, decrypting the cipher text stored in the data storage with the key in the data storage by using a decryption algorithm provided by the coder-decoder to generate plaintext data. In the embodiment of the invention, the key stored in the data storage is updated dynamically, so that the difficulty in acquiring the key with a plugin is increased, and the data security is greatly enhanced.