The invention discloses a speech quality improving method and system and a mobile terminal. The method comprises: obtaining, by the mobile terminal, a spatial position from the face of a user to the mobile terminal; determining audio parameters corresponding to the spatial position from the face of the user to the mobile terminal; adjusting audio parameters of a speech processing module of the mobile terminal to the audio parameters corresponding to the spatial position from the face to the mobile terminal; and outputting a speech signal, which is received from a network side, after being processed by the speech processing module, the audio parameters of which are adjusted. By means of the method, the hands-free frequency response and sensitivity can basically be kept in a relatively good state and can be basically kept unchanged, thereby avoiding the case of low frequency or medium-high frequency loss of a frequency response curve due to change of the distance or the angle from the mobile terminal to the face, improving speech quality in video call, and improving the listening effect of the user.