Abstract: The indentation size effect is discussed in detail through calculating surface plastic deformation around indentation by digital speckle correlation method (DSCM),testing hardness by different micro hardness-testing devices and finite element analysis(FEA).The results show that under different test conditions,surface deformation around the indentation correlates to the load and shows two states,and loads of changing surface deformation direction and producing indentation size effect are close.This indicates that the present indentatin calculation only using one model regardless the loads is unreasonable.So different models should be adopted when the indentation depth is different.