The present invention provides a method for reducing harmonic interference, an antenna device and a mobile terminal. The antenna device comprises an anti-interference module and a transmitting/receiving front-end module. The anti-interference module is connected to the transmitting/receiving front-end module. The anti-interference module is used for obtaining the first bit error rate of the auxiliary carrier component of the carrier and the port of the transmitting/receiving front-end module corresponding to the minimum bit error rate in at least one second bit error rate when the working frequency band of a carrier satisfies a preset condition, and controlling the transmitting/receiving front-end module to switch the channel of a main carrier component to the port corresponding to the minimum bit error rate. The device has the advantages of reducing the harmonic interference in carrier aggregation.