There are a lot of new phenomena for plastic flow at submicron scales.Apart from size effect,large strain burst accompanying dislocation avalanches are widely observed for face-centered-cubic (FCC) micropillars under uniaxial loading.[1,2] This large strain burst makes the stress-strain curve exhibit randomness,results in uncontrollable plastic deformation,and hence increases the difficulty in formation processes.[3]Thus,a clear understanding of the mechanism of large strain burst is desirable as a basis for increasing application performance of submicron crystals.