In this paper，an efficient feed—through assignment algorithm，FARM，is proposed to minimize the maximum channel density and at the same time to reduce，the wire length and via number．It connects the global routing with the channel routing．FARM consists of two parts：multi—row feed—through assignment and single row feed—through assignment．It is implemented in C language on DEC station 3100 and Sun—sparc2 station，and has been used in the Double—Layer CMOS gate array layout system— MALS3．Experiments on several benchmarks demonstrate FARM achieves comparable or better results comparing with TimberWolf 5．6．