The invention relates to an implementation method and circuit of multi-carrier/multiband frequency selection, which are used for implementing frequency selection of multi-carrier/multiband communication equipment. In the implementation method, each path of carrier/band uses the same local oscillator frequency Fo to carry out hybrid frequency in an upper link or a down link; and if the starting frequency of the ith path of carriers/bands of the multi-carrier/multiband communication equipment is shown as Fsi and the stop frequency of the ith path of carriers/bands of the multi-carrier/multiband communication equipment is shown as Fei, the centre frequency Fci of an intermediate-frequency filter which is used by the ith path of carriers/bands is equal to (Fei +Fsi)/2-Fo. The invention also provides a circuit of multi-carrier/multiband frequency selection. According to the method and circuit, one local oscillator circuit, one upper-conversion mixer and one down-conversion mixer can be shared by the multiple carriers/bands, thus decreasing equipment volume, reducing power consumption, reducing cost and shortening production time.