The invention relates to a method of enhancing system safety of broadcast and multicast, comprising: 1) a terminal registers to a base station: each terminal performs physical authentication and registration on the base station for providing service, and obtains an authorization key from the base station; 2) the base station performs broadcast/multicast process: 2.1) the base station constructs broadcast/multicast information cryptograph; 2.2) the base station transmits the broadcast/multicast information cryptograph to the terminal; 2.3) the terminal decrypts broadcast/multicast information cryptograph through the authentication key to obtain broadcast/multicast information plaintext. According to the invention, a broadcast/multicast safe network system is constructed, thereby solving the safety problems of the broadcast/multicast of the base station on the terminal in the network system.