An RF channelizer based on coherent optical processing is proposed.By employing two optical frequency combs (OFCs) with different free spectral ranges (FSRs) as opti cal carriers and optical local oscillators respectively,the channelizer can translate all of the frequency channels to a c ommon intermediate frequency (IF). The microwave signal is modulated on every optical carrier,and then all the mod ulated optical sidebands are filtered by an FP optical filter.Finally,the filtered optical sidebands are coh erently detected with the optical local oscillators,and the frequency down-conversion can be achieved.As the FSR of the carrier OFC is a channel bandwidth larger than that of the local OFC,and the FSR of the FP filter is equa l to that of the local OFC,the channel of common IF and bandwidth can be realized.Therefore,it is convenient for electron ic circuits design.Experiment measurements are demonstrated by translating two adjacent frequency-band range s over 9.74-9.86GHz and 9.86-9.98GHz into a 120MHz IF bandwidth.The center frequencies of two channe ls are 900MHz and 896MHz, respectively with merely 4MHz frequency difference.It is indicated that a comm on IF channel can be accomplished by this method.