Protium and deuterium permeation measurements were carried out with Pd8.5Y0.19Ru alloy membrane of 40 μm in thickness between 573 K-723 K. Fick's 1st pervasion law can be used to describe the hydrogen permeation behavior. The protium and deuterium permeability of the membrane and separation factors for the H-D gas mixture were obtained. The permeability expression of protium and deuterium are ΦH＝2.566×10-6exp(-3542.45/T) mol/m·s·Pa0.5 and ΦD＝1.398×10-6exp(-3443.72/T) mol/m·s·Pa0.5, respectively. Compared with Pd-Y binary alloy membrane, Ru element addition decreases the membrane’s permeability and the separation factors. Besides, CH4 has strong poison effect to the membrane.