Abstract: The Milligan oil droplet experiment has many influencing factors and the relationship between them

is complex，which leads to students' difficulty in understanding its experimental mechanism. The graphic analysis in

detail of Millikan oil drop experiment design helps to solve this problem. The experimental design idea as a main

story line，kinematics of oil droplets and relationship between experimental parameters are analyzed.

Key words: Milligan oil droplets, experimental design ideas, analysis in graphic, system parameters, experimental parameters