Abstract:The purpose of this study is to investigate boundary layer heights calculated by Richardson number method, inversion method and potential temperature gradient method, and compare them with Nozaki’s method based on L band radar sounding data in Beijing in November and December 2014. The similarities and differences of the boundary layer results calculated by the four methods during the two heavy pollution periods in 27 November to 1 December and 15-20 December 2014 are analyzed in details by using vertical profiles of meteorological elements and PM2.5 data in the same periods. The results show that the boundary layer heights calculated by Richardson number method, inversion method and potential temperature gradient method are 653 m, 1152 m and 1296 m in Beijing in November and December 2014 respectively, and the calculated boundary layer heights are negatively correlated with PM2.5 concentration in some degrees. The statistical probability results show that distribution of boundary layer heights below 500 m has the biggest probability, but there are some differences in other height ranges. Through the two typical heavy pollution periods, we found that different methods have applicability and limitation. Therefore, it is necessary to combine the vertical profiles of meteorological factors and pollutant concentrations with subjective judgment, which would help to determine the height of boundary layer.