Jet spreading plays a crucial role in process of fuel mixing in supersonic combustion. The jet preferred mode signifies the maximum spreading rate of the shear layer of jets under periodic excitation. In this paper, linear frequency response of compressible axisymmetric jets was analyzed based on an energy integral method. The jet preferred mode was numerically identified, and its dependence on various flow parameters were analyzed. The most interesting discovery of the analysis is that the jet preferred frequency, which is denoted by Strouhal number Stp= fpD/u0, is found to vary in non-monotonic manner with the jet exit Mach number M0. The implication of the result for mixing enhancement of supersonic jets with ambient fluids was also discussed.