The present invention provides a method for coupling the mobile terminal with the adapter. Firstly, coupling the mobile terminal with the adapter by RF induction; secondly, decreasing transmitted power of the mobile terminal so that the RF power leaking around is maintained below a specified value when the mobile terminal detects that it has been coupled with the adapter; finally, controlling the gain controlling means of the adapter by the mobile terminal to compensate the power loss due to the RF coupling and the transmitting power decreased by the mobile terminal itself, so that the transmitted power from the antenna of the adapter can reach the due power level transmitted by the mobile before it is coupled with the adapter. The structure of the mobile terminal is simplified and the price of the mobile terminal is decreased because the mobile terminal is coupled with the adapter through RF induction, and the RF changeover switch is not provided in the mobile terminal any more. Furthermore, the transmitting power in vehicle is always maintained below the European standard while the RF property of the mobile terminal is not degraded.