Abstract: The mechanical properties of high strength pure austenite welding wire deposited metals with two different Mo contents were tested, the impact fracture morphologies and metallurgical structures were studied by SEM, and the structures and composition of secondary phases were analyzed by TEM and XRD. The results showed that with the increasing of Mo content, the strength of deposited metal increased while the ductility and toughness decreased evidently; the main cause was a Mo-rich zone was formed near the grain boundaries because of the segregation of Mo; when Mo increased, concentration degree increased accordingly, which strongly promoted the formation of χ phase and increased the amount and size of χ phase; moreover the distribution of χ phase changed from being dispersed to along the grain boundaries in network, which resulted in the increase of strength and the decrease of ductility and toughness.