Molecular sieve is one of the natural gas dehydration methods. Separation of water from gas and reduction of outlet gas dew point to low level are some advantages of this method. In order to avoid icing and blockage of downstream pipelines and facilities, Molecular Sieve gas dehydration is required to assure the possibility of Ethane and Methane separation in low temperatures. This system includes some molecular sieve beds which are filled with molecular sieve adsorbent. These beds act as adsorbent column intermittently and then are regenerated with high temperature gas in lower pressure. After cooling, it will be ready to be in service again. Using of a control system (PLC type), makes it possible to accurately sequence the relevant processes i.e., adsorption, switch to the next bed, evacuation, heating, cooling and re-filling the bed.