Abstract: Palladium alloy membranes are widely used as permeator to produce pure tritium from impurities and tritride gas mixture in tritium technology related to fusion reactor. But long term continuous operation can lead to accumulation of 3He in alloy, and the results in tritium aging effects. In this work, the changes in protium/deuterium permeation characteristic of Pd8.5Y0.19Ru (at.%) alloy membrane induced by tritium aging were experimentally investigated. The aged membrane has a 3He atomic ratio of 0.042 to metal. The results show that in the temperature range of 573-723 K, the permeability of the aged membrane is decreased seriously, and the permeation separation factor for protium/deuterium is increased somewhat.