The temporal evolution of atmospheric convective boundary layer height (CBLH) has an important impact on weather and climate change, but there are few studies on the CBLH climatology over Beijing area. This study presents the CBLH climatology over Beijing by using high resolution ERA5 reanalysis data for the period 1992 - 2022. The ERA5 CBLH was first evaluated against radiosonde-derived CBLH. ERA5 can reproduced the CBLH variation characteristics by sounding reasonably well. Next, the interannual, seasonal and diurnal variations of the CBLHs, as well as the correlation between the CBLH and key meteorological parameters were analyzed. The results show that in the past 30 years, the CBLH in spring and autumn has decreased at the rate of 61.6 m per decade and 13.1 m per decade, respectively, while that in summer and winter has increased at the rate of 2.9 m per decade and 7.7 m per decade, respectively. The median value of CBLH at noon in spring, summer, autumn, and winter is about 1700 m, 1100 m, 950 m, and 800 m, respectively. The CBLH in spring is the highest among the four seasons, because of the large surface sensible heat flux and the weak atmospheric stability. By analyzing the relationship between CBLH and sensible heat flux, potential temperature lapse rate and Ts-Ta (surface temperature [Ts] and air temperature [Ta] difference), it is found that in spring, when the sensible heat flux increases by 100 W·m-2, the CBLH increases by 615 m. When the potential temperature lapse rate increases by 1 ℃·km-1, the CBLH increases by 1376 m. When the Ts-Ta increases by 1 ℃, the CBLH increases by 175 m.