The dynamic mathematical model of oil droplet falling in Millikan oil droplet experiment isestablished,and it is explained that the oil droplet can be regarded as the " rationality’of uniform velocity atthe beginning of falling.At the same time ,the physical meaning of the air viscosity coefficient correction factorb’is explained from the perspective of microscopic molecular collision.Finally, three experimental dataprocessing methods, direct substitution formula method, modified R formula method and iterative operationmethod,are used to calculate the element charge value, and the conclusion that the data obtained by theterative operation method is more stable and the error is small is obtained.