Abstract: In order to simulate the propagation of X-ray thermal shock wave under the three-dimensional condition, an appropriate resolution of energy deposition calculation is needed to be found. In this paper, an algorithm of accumulating the energy deposition for X-ray in hexahedron element was proposed via calculating the integral of the energy flux vector on the surface element. Furthermore, the distribution of the energy deposition of finite-length cylindrical shell was calculated under both normal incidence X-ray and oblique incidence X-ray separately. The results show that the energy deposition is approximate cosine distribution along the azimuth under the normal incident, which agrees with the theoretical solution, and the energy deposition decreases rapidly from the surface layer to the interior under the direction of radius. Meanwhile, for the oblique incident, the energy deposition areas appear in both outer and inner sides of the shell and the end surface of the cylinder, and the boundary effect is well presented in the distribution of the overall energy deposition.