The experiment of Millikan oil-drop uses the principles of electricity and mechanics to analyze the oil droplets motion Trajectory under the action of electric field and gravity,and then calculate the charge of oil droplets.Moreover,in order to measure fractional charge,people carry out relevant re-search and expansion experiments which based on this method.By researching the purpose and principle of the Millikan oil-drop experiment,and using the simulation experimental platform which produced by the development of computational technology.Students do this modern physics experiment again through the simulation step method,which makes students have a comprehensive understanding about charge measurement and simulation experimental teaching.Simulation experimental teaching increases students'interest in learning physics experiments greatly.