Objective To analyze the radiation doses to surroundings and medical staffs during positron emission tomography-computed tomography (PET-CT) examination of malignant tumor patients. Methods Sixty-two patients with malignant tumors who underwent PET-CT examination in Hongkou Branch of The First Affiliated Hospital of Naval Medical University (Second Military Medical University) from Jan. 2019 to Aug. 2020 were enrolled. The radiation doses to the surroundings of patients, medical staffs and the workplaces were detected, including the equivalent dose rates at 1, 2 and 3 m away from the subjects and each monitoring point in the waiting room, PET-CT room, doctor's office and injection room, and the annual effective doses of medical staffs. Results The equivalent dose rates at 1, 2 and 3 m away from the subjects were (4.40±0.64), (1.82±0.61) and (0.87±0.35) μSv/h, respectively, and the equivalent dose rate at 1 m away from the subject was higher than that at 2 and 3 m (both P<0.01). The equivalent dose rates at outer surface of protective door of waiting room, fume hood hand hole of injection room, hand hole of injection table, and positions of injection table staff were higher than those at other monitoring sites, such as outer surface of the protective wall and surface outside the protective door of the injection room (all P<0.05). The annual effective radiation dose of operation technicians was 0.82 mSv, which was higher than that of other involved staffs, such as waiting personnels and auxiliary operators. Conclusion The equivalent dose rate at 1 m away from PET-CT subjects is higher than that at a longer distance. The equivalent dose rates at outer surface of protective door of waiting room and fume hood hand hole, hand hole of injection table, and positions of injection table staff of injection room are higher than those of other workplaces.