A split-shaft gas turbine adapted from WZ5G aeroengine is quite suitable for driving a booster compressor station in a long gas pipeline. A mathematical model is established for a booster station with two series centrifugal compressors driven separatelyby the split-shaft gas tnrbine of WZ5G aeroegine. The model is simplified by a static state optimization. Its transfer functions are obtained through a nonsin-gulartransformation. The model is applied to analysing the stability and dynamic responses of the system. Some conclusions are drawn which are helpful to controllingof the long gas pipeline.