Abstract: When high-current pulse electron beam of 20 MeV is focused onto the bremsstrahlung conversion target, high intensity pulse X-rays are produced. At the same time, a large amount of energy is deposited into the target, which results in the target material expansion and blowing off. X-rays doses may be reduced significantly when multi-pulse beam interacting with the conversion target, because the density of the target material decreases during the beam pulses. In the paper, the Monte-Carlo code MCNP and hydrodynamic code ANSYS AUTODYN were used to simulate the hydro-response of the target material and the X-rays dose of each pulse. The results show that X-ray doses are only slightly reduced when 3 pulses (20 MeV, 2 kA, 70 ns, spot size 1.5 mm (FWHM) and 500 ns separation) impacting on the conversion target.