Abstract: To study the corrosion behavior of new domestic Zr-Nb alloy, specimens were exposed under different conditions, including 350 ℃ static water with lithium and boron, 500 ℃ steam by autoclave, and dynamic water with heat flux of 100 W/cm² on the surface of the specimens by out of pile loop. The microstructure of new Zr-Nb alloy was characterized by transmission electron microscopy (TEM). The morphology of oxide films was investigated by optical microscopy (OM). The hydrogen pickups were measured by inert gas fusion and IR detection, and hydrides were also observed by OM. The results indicate that new Zr-Nb alloy has superior in corrosion resistance to optimized Zr-4. The microstructure of alloy analyzed by TEM shows that fine and uniformly distributed second phase particles are beneficial for improving corrosion resistance of Zr-Nb alloy.