Abstract: Effects of Cu, Ni and Mo on the isothermal transformation,austemperability and mechanical properties of ductile iron weld metal were systematically investigated and the matrix structure of austemoered ductile iron weld was examined with scanning electron microscope and transmission electron microseope.On this basis a Ni-Mo low alloy electrode for arc welding of austempered ductile iron was developed for the first time,The austemperability of the Ni-Mo low,alloy weld metal increases by 2.5 times as compared with that of the unalloyed weld metal and the mechanical properties of the weld and welded joint can match the requirement of austenpered ductile iron.