Lakes played an important role in regulating local climate and air quality. The impact of urban lakes on urban local atmospheric boundary layer circulation and atmospheric pollutant transport mechanisms was an important issue in current urban air quality research. This study analyzed the diurnal variation characteristics of near-surface atmospheric pollutant concentrations at lakeside stations in urban Nanjing in summer, and compared them with observations from non-lakeside urban stations relatively far away from the lake. The results showed that for NO2, which was mainly emitted near the ground, the average concentration in lakeside stations was about 1.64±0.29 μg·m-3 higher than that in non-lakeside city stations during the day, and was about 0.51±1.39 μg·m-3 lower at night. O3, which was mainly generated and transported in the middle and high levels of the boundary layer, showed the opposite trend: that is, the average concentration of lakeside stations during the day was about 9.57±2.19 μg·m-3 lower than that of non-lakeside city stations, while it was about 1.24±4.68 μg·m-3 higher at night; No similar concentration differences were found in PM2.5. We further used a two-dimensional land surface process model to conduct numerical experiments on the sensitivity of lake land use to lake-urban land distribution and different emission scenarios. The simulation results showed that the difference in thermal properties between lake surfaces and land surfaces in urban areas affects low-altitude atmospheric circulation. and vertical thermal stability, and further affected the diffusion and transmission process of urban near-surface air pollution concentration. Affected by the existence of the lake, the thermal stability of the vertical atmosphere above the lake and lakeside area during the day was higher than that over the non-lakeside area, and the vertical diffusion of the lower atmosphere was weaker, resulting in higher concentrations of pollutants mainly emitted near the surface in the lakeside area. The concentration of pollutants mainly emitted and generated at mid- and high-altitudes was low, while the situation was opposite at night. The simulation results were consistent with the observed data trends and qualitatively consistent with the WRF-Chem simulation results.