ETRI successfully developed the Ka-band EQM (Engineering Qualification Model) communications and Broadcasting Satellite (CBS) payload system in cooperation with the Korean domestic companies, such as Korea aerospace Industries (KAI). Korean Air (KAL), Telwave and KoSPACE in order to technically verify its required performances without any failures in a simulated launching and space environments. The Ka-band CBS payload system consisted of a bent-pipe type of transponder and an antenna subsystem. Each subsystem was also appropriately composed of its relevant equipment. The reliability of the developed target system was analyzed in worst case and the analysis results turned out that allocated values of the system well complied with the required values. In addition, the reliability allocation methods of the developed target system are briefly described and its assessment methods are also discussed and demonstrated.