The electrostatic potential energy distribution of polyelectrolyte gels has been modelled and simulated on the basis of Poisson-Boltzmann equation. The simulation was carried out with a three dimensional network model. The simulation reveals that there exist deep electrostatic potential wells at every crosslinking point and potential valleys around the polymer chains. The simulation results also indicated that a strong electrostatic field exists near the polymer chains especially around the crosslinking points. Various abnormal phenomena observed in the polymer gel, such as the presence of non-frozen water, higher electroconductivity at low temperature, electrocontractile behavior, etc., are considered to be associated with the presence of this strong electric field.