Two kinds of security chips having a security interface are provided. One kind of security chip comprises a processor module, an encrypt/decrypt module, a memory module, a power detecting module and a security I/O module, and all of the modules are connected with each other by an internal bus in the security chip; the other kind of security chip comprises a processor module, an encrypt/decrypt module, a memory module, a power detecting module and an I/O interface module, all of the modules being connected with each other by the internal bus in the security chip, wherein, the security chip also comprises a security input module, a security output module and a south bridge interface module, and all of the modules are connected with each other by the internal bus in the security chip. With the security chip provided by the present invention, it is possible to encrypt/decrypt the I/O information of an information processing device, ensure the safety of the I/O information, and thus prevent the information from being listened to or otherwise revealed.