Powerflow of double-deck isolation systems is analyzed by using the powerflow theory and the Four-end parameter method, and an analytical method on powerflow of vibration transfer paths is studied. Combining with the Kronecker algebra, the generalized second moment method, the perturbation theory, the probability and statistics, the calculation method of double-deck isolation systems is obtained. The random powerflow of vibration transfer paths are described correct ly and expressly in frequency range. A new method is provided to analysis powerflow of vibration transfer paths.