This work aims to investigate the effects of 800 keV argon ions pre-damage on the following deuterium plasma irradiation behavior in tungsten-tantalum alloy (5 wt% tantalum dopant). The un-damaged and pre-damaged W-5%Ta were exposed to 60 eV deuterium plasma at a fluence of 1.944 x 10(26) D/m(2) in the linear plasma device. The results suggest that pre-damaged induced by Ar8+ ions can effectively mitigate deuterium-induced blistering, while the deuterium retention is significantly higher as compared to the undamaged W-5%Ta. According to the transmission electron microscopic (TEM) analysis, a large number of defects can be observed clearly after irradiation by 800 keV Ar8+ ions, such as vacancies and dislocation loops, which eventually affect the surface blistering and deuterium retention in W-5%Ta. Furthermore, we also compared the deuterium retention in pre-damaged pure W, which was significantly increased by a factor of 15 than in predamaged W-5%Ta. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.