Abstract: With multiple scattering theory of electrons we studied energy deposition of electrons within target and energy distribution on spot of X-ray production by Monte Carlo method as energetic electrons impinge into target vertically. It shows that spread of electrons within target is relevant to incident electron energy and target material. And 99% electron energy is deposited in a cylindrical zone. Energy deposition of electrons along incident direction increased with depth first, and then to a certain depth it decreased rapidly, which is in accordance with electron backscattering theory. These results illustrate that X-ray production zone is within a certain depth under target surface. In addition, simulation results of diamond indicate that diamond film is not recommended as an electron absorption grating, but as an excellent heat sink of target. It can be used as reference for design of microstructure X-ray tubes.