The surface potential and electron yield dynamic characteristics of an insulating thick sample under high-energy electron beam irradiation are obtained by combining the numerical simulation and experimental measurement. The numerical model takes into account the electron scattering, charge trapping, and charge transport. The results show that due to the electron scattering and transport, the space charge is weakly positive in the near surface and strongly negative inside sample; along the depth direction, the space potential decreases to a minimum value slowly, and then increases gradually and finally tends to zero; with the electron beam irradiation, the surface potential decreases to the negative kV magnitude gradually, and the total electron yield gradually increases to a stable value that is slightly less than unity. After stopping irradiation, the surface potential increases gradually, but charges are not eliminated completely. The surface potential decreases linearly with the increase of the beam energy, and increases with the increase of the incident angle, however it decreases slightly with the increase of the sample thickness.