Abstract: The impact toughness of metal deposited by high strength austenite electrodes with different carbon content was tested.The microstructure of the impact fractures and the eroded samples were analyzed by SEM.The second-phase was analyzed with the energy spectrometer and the TEM.The solidifying phases and the content of second-phase were calculated with the thermodynamic simulation software.The results indicate that the impact toughness reduces with the carbon increasing.The main cause is that the increasing of carbon content induces the shape changing from particles to slices, the dimension and the content increasing of the carbides forming in the solidification.The carbides weaken the continuity of the austenite base.And the brittle carbides crash easily in the crack spreading.These reduce the impact toughness of the deposited metal.