In this paper, the hydrogenation-desorption technology was applied to process as-cast ZK60 alloy, and the nanocrystallization mechanism in this processing was studied. The phase and microstructure evolution of ZK60 alloy powders at different states (before hydrogenation, after hydrogenation and after desorption) were characterized by powder X-ray diffraction, optical microscopy and transmission electron microscopy, respectively. The results reveal that ZK60 powders are completely hydrogenated at 450 ℃ under 2 MPa for 12 h and then thoroughly dehydrogenated at 350 ℃ for 3 h in vacuum; meanwhile, the grain sizes of ZK60 alloy powders are refined from 150 μm to 30 nm as well.