Peening is a surface treatment method to improve the fatigue life of engineering components. Recent development of peening technique such as laser-shock and cavitation shotless peening were introduced as an alternative to conventional shot peening. Previous study has shown that cavitation shotless peening (CSP) was not only introduce macro-strain onto the surface of components but also simultaneously relieve micro-strain of quenched metallic materials. In order to get a better understanding on the mechanism and the extent of the effect of CSP on macro- and especially micro-strain, as compared to shot and laser-shock peening, we propose Bragg-edge transmission imaging study at IMAT. Through Bragg-edge analysis, 2D map of macro- and micro-strain and it's evolution due to different types of peening and different peening parameters can be observed.