Abstract: The level and change of radioactivity in the air of three areas in Yunnan Province were determined by the content of radionuclide in aerosol. The aerosol was collected using a very large flow sampler and compressed and sealed for 20 days, and then analyzed by high purity germanium gamma spectrometer.The results showed that 210Pb and 7Be could be detected and fluctuated in the normal range. Other nuclides were not detected.Through a year-long monitoring, the radioactivity level of γ nuclide in aerosols in these three areas fluctuated in a normal range, and the fluctuation was affected by seasons and precipitation.