The invention discloses a wireless intelligent key device and a signing method thereof, belonging to the field of information security. The wireless intelligent key device comprises an online apparatus and an offline apparatus, wherein the online apparatus comprises a controller module as well as a serial communication interface and a first wireless receiving/transmitting module which are connected with the controller module; and the offline apparatus comprises a security module as well as a power module, a second wireless receiving/transmitting module and an information input/output module which are connected with the security module. The signing method comprises the following steps: the online apparatus is powered on, receives the transaction information message distributed by a host and sends the transaction information message to the offline apparatus; the offline apparatus analyzes the transaction information from the transaction information message and outputs the transaction information; the offline apparatus judges whether to perform the signing operation according to the received user operation information, and sends a corresponding operation result to the online apparatus; and the online apparatus sends the operation result to the host. The device disclosed by the invention is convenient for the user to carry and operate; and during signing, the online apparatus and offline apparatus can communicate in a wireless manner or wired connection manner.