Abstract: In this paper, the Monte Carlo method and finite element analysis software were used to analyze electronic energy deposition and heat transfer process during the electron bombardment of the target in the fixed anode X-ray tube. The anode is made up of copper rod and tungsten film. With different duty cycles, sizes and shapes, the focal temperature rising process of tungsten film with different thicknesses and the adjacent copper was calculated. The result shows that there is an optimal value of tungsten film thickness depending on the working conditions. In pulse imaging mode, the fixed anode is able to withstand large beam intensity. Therefore, the development of a field emission cathode X-ray tube with maximum voltage of 140 kV, maximum current above 10 mA, effective focal spot diameter below 1 mm is feasible.