Coal bed methane(CBM) has a huge potential to be purified to relieve the shortage of natural gas meanwhile to weaken the greenhouse effect.This paper proposed an optimal design strategy for CBM to obtain an integrated process configuration consisting of three each single separation units,membrane,pressure swing absorption,and cryogenics.A superstructure model was established including all possible network configurations which were solved by MINLP.The design strategy optimized the separation unit configuration and operating conditions to satisfy the target of minimum total annual process cost.An example was presented for the separation of CH₄/N₂ mixtures in coal bed methane (CBM) treatment.The key operation parameters were also studied and they showed the influence to process configurations.