The spatial profile of the energy deposition for the main amplifier (H1M) of a KrF laser MOPA system is presented by meams of 3D Monte Carlo method. The effects of Hibachi structure and main foils are considered. For 0.5 MeV electron, the energy deposition distributions of pumping direction are almost uniform. In the lasing direction (axial), because of a 14 cm unpumped area between two e beam windows the spatial profile of energy deposition takes the shape of a saddle. The peak valley ratio is 2～3. In addition, the relations of the total deposition energy and the energy deposition efficiency with the e-beam energy are given. The total deposition energy and the energy deposition efficiency reach the maximum when the e-beam energy is equal to 0.5 MeV and 0.31 MeV, respectively.