The present paper aims at revealing the formation mechanism of craters on the surface of metals produced by the bombardment of a high-current pulsed electron beam. Based on experimental investigations and a physical model, the temperature field and melting process are simulated for Al and two kinds of steels. The star ting melting positions, largest crater depths, and melting layer thicknesses are obtained, which agree satisfactorily with experimentally observed values. It is confirmed that temperature rises faster at a sublayer instead of on the extreme surface due to the maximum energy deposition located at about 1/3 of the total penetration depth of the beam. Such a special sublayer heating and melting mode causes eruptions of the sublayer liquid through the outer surface and produces t he typical surface crater morphology.