High resolution transmission electron microscope (HRTEM) is widely used in the study of various RRAM materials system. HRTEM can provide detailed cross sectional characterization of RRAM devices with compositional and structural information at the same time. Recently, scanning probe microscopy (SPM) techniques have also been explored to study oxygen vacancy based RRAM switching with detailed surface, electron energy and tomography information. This paper will introduce the recent RRAM switching studies enabled by advanced physical analysis techniques.