A method for pre-accessing a conference telephone is disclosed in the present invention. The method includes that: a network side detects a received call whose target is a main control party after the main control party initiates an encryption conference telephone; the call is not accessed if the call is a non-encryption conversation; the call is allowed to be accessed if the call is an encryption conversation. A system for pre-accessing a conference telephone is also disclosed in the present invention, wherein, the system includes a pre-accessing processing unit and a call type detection unit of the network side. A network side device is also disclosed in the present invention. The present invention realizes the pre-accessing of the encryption conference telephone, thereby improving security of the encryption conversation as well as avoiding the problem that a user is frequently affected when performing the encryption conference telephone.