Abstract: In the primary CNG filling station of phase 1 pipeline project of Jiangxi Natural Gas Co, Ltd., absorption capability ca nnot restore after molecular sieve regeneration so that water cut after the dehydration of natural gas exceeds the national standard, thus affecting steady operation of equipment and normal gas supply to downstream users. Deviation between design parameters and working parameters and technological process defects of the dehydration device are analyzed. In accordance with the analysis results, regeneration process of the dehydration device is transformed from twotower open cycle to one-tower closed decompression cycle. After the transformation, one-tower adsorption cycle of dryer in the primary CNG filling station increases to 136 h from the previous 5 h, so that the adsorption capacity is significantly improved to reduce the regeneration costs. The transformation program can provide a reference to the processing of similar problems in the same industry.