Abstarct: With regarding to increase of energy price, limitation of production resources and maintenance of the environment, it is necessary to reduce the energy consumption and optimize the consumption; on the other hand, it displays the utilization of pure energy resources. Liquefied natural gas is one type of pure energy resources that energy consumption of production process is high due to low temperature levels of cryogenic supply. On one hand, being some of the industrial countries far from gas resources lead to the natural gas export study in these areas. Survey and study on natural gas liquefied units is important to improve them and to reduce the energy consumption. For transporting the gas by means of pipe line to consumption areas, gas pressure should be increased till the feasibility of gas transportation will be provided, but, when you utilize it at homes, pressure should be decreased again that this pressure reduction is being done in city gate station. so, we deal with different cycles of liquefied natural gas production (Prico, mini and expander ) in this survey , respective cycles is analyzed by HYSYS software and effects of factors such as inlet temperature , inlet pressure, inlet natural gas rate are examined till energy consumption in liquefied natural gas production cycle will be minimized. Then, a method will be recommended that these cycles would be used in city gate station. Results show that using the liquefied natural gas production cycle in city gate station will reduce work per LNG unit. Increasing inlet pressure and inlet gas temperature reduction are also reducing the amount of gas consumption of LNG unit.