First, we give a uniform electric field with an electric field intensity of E0. Then we put in an uncharged conductor. Then, due to the different potentials at the two ends of the conductor, the internal charge will move, the positive charge will move to a low potential, and the negative charge will move to a high potential. The original electrostatic balance is broken, and after reaching a new balance, the charges at both ends of the conductor will form an additional electric field E'. After the balance, this E'=E0, in the opposite direction. If they are not equal, it means that there is still an external electric field and the charge will move, which is inconsistent with the premise. At this time, the internal electric field of the whole conductor is formed by superposition of external electric field E0 and additional electric field E', and its sum is 0. The surface potentials are equal, but not zero. It is worth noting that the conductor is charged due to electrostatic induction, so the electric field in the whole space is no longer uniform after its electric field is superimposed with the uniform electric field, and it needs to be recalculated.