A multimode terminal includes a first modem chip, a second modem chip, a switch connected to both the modem chips, and at least two antennas connected to the switch. The first modem chip includes an antenna selection apparatus configured to select an optimum antenna for the first modem chip, control the switch to connect the first modem chip to the optimum antenna of the first modem chip, determine an optimum antenna of the second modem chip according to a related parameter value of a signal received or transmitted by the second modem chip, and control the switch to connect the second modem chip to the optimum antenna of the second modem chip. The second modem chip includes a measurement apparatus configured to measure the related parameter value of the signal received or transmitted by the second modem chip.