Abstract: Presented the virtual channel control unit and VCDU(virtual channel data unit) multiplexing unit based on the AOS(advanced orbit system) recommendation,which were prepared by consultative committee of data system.They were designed to support bitstream service and VCA(virtul channel access) service and provide B_PDU(bitstream protocol data unit) construction function,VCDU assembly function,VCDU commutation function,fill generation function and delimiting function.The units were designed by FPGA(field programmable gate array),suit defferent frequences and several sources.The design amalgamates the payload datas and the platform datas,transmits the bitstream through one channel,makes the satellite more agility,more open,more available.The work on this item can saving frequency resources,sustain broad band transmission,boost up the administer ability of the satellite.It is a pre-research program and it is the implementations of advanced orbiting data systems,which are used on satellites.