1. A signature rule processing method, comprising: receiving, by a cloud server, signature rule usage status information, which is sent by at least one security device connected to the cloud server, of each of the at least one security device, wherein the signature rule usage status information of a security device is used to indicate a usage status of a signature rule of the security device in a whole network; performing, by the cloud server, correlation analysis on the signature rule usage status information of each of the at least one security device and a latest signature rule set published by the cloud server, to obtain a most active threat signature rule identification list; generating, by the cloud server according to the most active threat signature rule identification list, update information corresponding to each of the at least one security device; and separately sending, by the cloud server, the update information to each of the at least one security device, to drive said security device to update a signature rule according to the update information.