Abstract: This paper studies the effect of the initial values of different potentials on the surface potential attenuation of spacecraft dielectric materials. The method is as follows: charge the PI and PTFE dielectric materials to different potential values using spacecraft simulation equipment, then close the electron gun and measure the attenuation curve of the surface potential of the dielectric material with a potentiometer, and theoretically analyze the cross-over phenomenon. The result shows that, the higher the initial potential value of the dielectric material, the faster the surface potential decay rate, and the potential decay efficiency increases with the initial potential value in a certain period of time, under the same vacuum condition, for the two sets of attenuation curves with the same sum of initial potentials, the closer the initial potential values are, the more likely the cross-over phenomenon will occur; the time at which the cross-over occurs is related to the mobility of the electrons, under the same initial potentials, the longer the mobility, the shorter the time before the cross-over occur and the faster the potential attenuates. It is concluded that the values of the charge potential on the surface of the spacecraft affects the attenuation efficiency and the decay rate of the potential.