A method for controlling effective time of a terminal trigger message is disclosed. The method includes: a mobility management unit receives a terminal trigger message from a Machine Type Communication (MTC) application server; and in a scenario of congestion control, the mobility management unit determines that a time value of a back-off timer is longer than a time value of an effective timer related to the terminal trigger message, and reconfigures the time value for the effective timer related to the terminal trigger message. A system for controlling effective time of a terminal trigger message is further disclosed. With the present disclosure, before the back-off timer of a terminal expires, a network can reserve the trigger message to avoid an unsuccessful trigger of the terminal, thus improving a success rate of triggering the terminal.