A Simple and easy method is used for preparation of the electrostatic field specimen In this paper. On account of following physical factor, some dielectric particles supported by a thin carbon film, for example, polystarene latex spheres, 0.31 m in diameter, will become a charged body during the observing in electron microscope because of electrostatic aocomnlation. Obviously, under the electron beam, the spheres, of radius r, acquire a stationary positive charge Q, and the resulting field can be simply modelled by that of a point charge Q. With the field model, the electrostatic field distribution were observed and the magnitude of the charged quantity is determined by electron holography.