Method and device for updating pws key

Disclosed in the present invention are a method and device for updating Public Warning System (PWS) key。 According to the said method，when a preset condition is satisfied, UE receives updated PWS key from a network side device via a downlink NAS message; UE updates the current PWS key with the received PWS key. According to the technical solution provided by the present invention, the PWS security protection is enhanced by updating the PWS key in real time.