The application of main radionuclide in the department of nuclear medicine in a large-scale Hospital are introduced; Radiation levels of gamma-rays and gamma-ray in all the workplace are monitored. It has been found that the highest gamma-ray radiation level is in the Leaching-packing room, and the highest gamma-ray radiation level is in the temporary waste storage box. Possible impacts of main radionuclide on public and the staff are evaluated and according to the actual situation, the controlling measures of reducing the pollution are expounded, finally, the major evaluation conclusions are given and several suggestions about solving the pollution are proposed.