Abstract: To further understand the radiation characteristics of medical diagnostic X-rays and verify the feasibility of computer-based energy spectrum simulation methods, two Monte Carlo simulation programs, EGSnrc and MCNP5, were used to construct simplified models of irradiation devices. These models simulated X-ray energy spectrum distributions under various tube voltages and additional filter thicknesses, establishing an energy spectrum database for the RQR series radiation qualities. Results demonstrate that tube voltage and filter materials significantly influence X-ray energy spectrum distribution. In clinical practice, when the anode target angle of X-ray equipment is predetermined, accurately setting the tube voltage, regularly monitoring radiation quality changes, and making necessary adjustments to additional filtration are essential measures to ensure consistency in medical diagnostic equipment measurements. Comparative analysis of simulation results from both software packages shows that the difference in average energy is less than 2%. EGSnrc demonstrates advantages in ease of use, high simulation efficiency, and convenient data processing during simulation calculations.