Abstract: High-energy flash radiography is the most effective technique to interrogate inner geometrical structure and physical characteristic of dense materials. It is shown that high-energy proton radiography is superior to high-energy x-ray radiography in penetrating power, material composition identification and spatial resolution. Proton radiography is taken as a leading candidate for the Advanced Hydrotest Facility by the United States. The project and current development in high-energy proton radiography is reviewed.