Abstract: According to the formula of the electric field due to finite unifomfly charged line and the superposition of electric field, this article gives a new method to calculate the electric field of finite uniformly charged cylinder with excavated a small cylinder, （in vacuum） which is easier, faster and more definite than the method using elliptical integral. Furthermore, discussion and simulation of the cases that arbitrary number of small cylinders are excavated are presented.

Key words: electric field, finite charged cylinder with excavated a small cylinder, simulation, digital teaching