The dynamic stability of fluid conveying piping system under different supporting conditions, considering the fluid structures interaction, was investigated. The expression of vertical vibration mode-function of commonly supported piping system was derived from its boundary condition of the similar beam. Firstly, considering the effects of Kelvin-Voigt visco-elastic coefficient of pipe, fluid pressure and axially sectional force of pipe, the motion equation of the piping system was established. Secondly, the equation was discretized by Galerkin method according with its similar supporting conditions of beam. Thirdly, the expression of critically instable flow velocity was obtained. Lastly, the stability of the piping system was analyzed by using the dynamical simulation methods. The numerical results showed that the critically instable flow velocity is proportional conversely to supported linear spring coefficients, but is proportional to restrained torsion spring coefficients.