With the adjustment of energy strategy, the demand of natural gas as clean energy will increase dramatically. Because of the uneven regional distribution of natural gas resource in China, the transportation pipeline networks have been developing quickly in recent years and the pressure of the pipelines is also becoming higher and higher. The pressure energy in the pipelines is enormous. A novel cycle recovering pressure energy of natural gas transportation pipelines by vortex tube is presented in the paper. The high pressure natural gas expands in the vortex tube into two flows, and then the lower temperature flow out of the vortex tube cold end gets into the heat exchanger to cool the compressor inlet air. Then the cold flow recovers the heat of the smoke before exhausting to the atmosphere and then mixed with the higher temperature natural gas flow out of the hot end of the vortex tube. The mixed gas is introduced into combustion chamber. The cycle will increase the efficiency of the gas turbine cycle and the utilization rate of energy.