Abstract: Studies on the high energy ion beams generated in ultraintense laser－plasma interactions has made considerable progress recently due to the development of high power laser technologies. Ion beams of small source size, high brightness and collimation in laser plasma interactions have attracted great interest because of a wide range of important applications, such as advanced proton radiography, fast ignition of inertial confinement fusion, tabletop ion accelerators, and medical applications. This paper discusses the generation mechanisms, beam characteristics, diagnostics, potential applications and recent studies of high energy ions, especially protons, produced by irradiating solid targets with ultra－intense laser pulses.