The invention discloses an echo eliminating device, comprising: an acoustic echo eliminator which receives an echo time-delay value and determine parameters according to the echo time-delay value to eliminate the echo; a downlink voice detecting module which detects whether energy of a received downlink voice signal reaches the prearranged threshold value, if so, an identifier is output; a time-delay computing module which collects the uplink, downlink voice signals, computes correlative coefficient of the uplink, downlink voice signals at the time of receiving the identifier, determines the echo time-delay value corresponding to the maximum value of the correlative coefficient, and sends the echo time-delay value to the acoustic echo eliminator. The invention not only can configure appropriate parameters for terminal by the time of leaving factory, but also can be integrated to update relevant parameters in real time for a part of the acoustic echo eliminator, thereby the invention is apt for variation of the echo time-delay owing to change of the terminal's circumstance and improves effect of echo elimination as well as reduces expenditure of system resource. Meanwhile, the invention also discloses a communication terminal including the echo eliminating device, and a method for determining the echo time-dealy.