Abstract: In this paper, we have derive the dispersion relation, and growth rate of Alfven wave in the presence of parallel electric field in Saturn magnetosphere has been applied to the magnetosphere Saturn to the observations made by Cassini.s. The effect of parallel electric field is included in the zeroth order distribution function through modification of the electron thermal velocity parallel to ambient magnetic field. It is found that the parallel electric field of the electrons enhances the damping/growth rate of the wave according to the direction of electric field. The applicability of theory for the space plasma has been discussed.