Abstract: Herein,we addressed the performance evaluation of the electron flood gun,a key component of the state-of-the-art scanning electron microscope used in integrated circuit and materials science industries to prevent surface charge accumulation interference on nonconductive sample,with the lab-built test platform,comprising the scanning Faraday-cup with a bottom aperture,host computer,3 D-position manipulator,pumping and control units. The properties of the home-made electron flood gun,including the spot size,radial density distribution and divergence angle of the electron beam were automatically characterized in real time with the test platform,operating in Faraday-cup aperture "scanning" method.The test results show that the lab-built test platform works pretty well.We suggest that the test platform be of some technological interest in design optimization of electron flood gun for industrial SEM.