Abstract: In this paper,the cylindrical plasma-loaded Cerenkov FEL is studied usingfluid theory.It is shown that its working frequency and linear growth rate are higher than thatof common Cerenkov FEL,and for the same injection current,the linear growth rate of thissvstem and common Cerenkov FEL either decrease with increase of the gap between the dielectricand electron beam or there is an optimum gap value corresponding tO the maximum growth rate.