Abstract: Effect of carbon and nitrogen on microstructure and properties of austenite weld metal were studied by scanning electron microscope, transmission electron microscope and other methods. With increasing C content, the quantity of M₂₃C₆ carbide particles at austenite grain boundaries increased and the size of M₂₃C₆ enlarged. The tensile strength of deposited metal increased, however, the toughness decreased markly. When the content of C increases to a high level, the solution strengthening effect doesn't express anymore, but the quantity and size of carbide particles formed at austenite grain boundartes is still increasing. The toughness and intergranular corrosion resistance decreased continuously. With increasing N content, tensile strength increased, at the same time, the toughness kept at high level. Owing to small quantity of carbide particles formed at austenite grain boundaries, intergranular corrosion resistance displayed good performance.