Abstract: In order to effectively protect astronauts from space radiation, a finely detailed male voxel phantom was created using computed tomography (CT) data. A Monte Carlo program based on Geant4 was established to calculate orbital radiation doses in the phantom after the radiation passing through the module wall of the space station (equivalent to 5 g·cm^-2 of aluminum shielding). The absorbed dose, equivalent dose, and effective dose of various radiation particles in the voxel phantom's tissues or organs were analyzed. The results show that approximately 80% of the absorbed dose in astronauts is from Earth radiation belt (ERB) protons; approximately 14% is from galactic cosmic ray (GCR) protons; and alpha particles accounted for about 5% of the dose contribution; the contribution of other heavy ions to the absorbed dose was around 1%. In addition, approximately 50% of equivalent dose and effective dose received by astronauts came from ERB protons, while the other 50% came from GCR. The calculation results will aid in evaluating the potential radiation risks received by astronauts aboard the space station and provide a reference for radiation protection.