Since the AC voltage is applied to the cable, the electric field value in the vicinity of water tree will continue to change over time. It is difficult to measure the electric field experimentally which will change in a short period of time. In order to calculate the electric field values of the water trees and to visualize the electric field in the vicinity of the change to water trees, simulation works are carried out by using a circuit simulator (LTspice). Our works can be helpful to understand the phenomena of water tree in the cables.