The underlying surface of China is complex and the driving factors of the boundary layer are numerous. At present, there is a lack of comprehensive analysis of the boundary-layer height and its influencing factors all over China. This paper uses the K-prototypes algorithm to cluster the boundary-layer height and its twelve possible influencing factors and studies the regional features of the boundary-layer height and its dominant influencing factors in summer over China, based on the high-resolution radiosonde measurements from CRN from 2012 to 2016. The results show that the boundary-layer height of the 100 stations at 08:00, 14:00, and 20:00 can be divided into four regions: northeast of China, southeast of China, northwest of China and southwest of China. On this basis, the paper then analyzes the dominant influencing factors of the boundary-layer height in different regions at different times, and studies the possible mechanism of how these factors affect the development of the boundary layer under different thermodynamic conditions. The results suggest that the development of the stable boundary layer at 08:00 and 20:00 is mainly affected by the turbulent dynamics of the wind speed, while that at 14:00 is closely related to intermittent turbulence. The development of the neutral and convective boundary layers is also mainly driven by wind speed in the morning, while at noon it is mainly driven by the turbulent thermal caused by higher surface temperature and larger net surface radiation flux. What’s more, the cloud amount and specific humidity in the northeast, the latent heat flux in the southeast, the sensible heat flux and specific humidity in the northwest, and the sensible heat flux and soil moisture in the southwest can also affect the development of the neutral and convective boundary layer through direct or indirect effects on thermal turbulence. At night, because of the time difference, wind speed tend to be the main influence factor of the neutral and convective boundary layer height in the east of Chine, while in the west of China, the main influence factors may still be the thermal factors. In addition, the leaf area index in the north of China regulates the specific humidity by vegetation transpiration, and the specific humidity can affect the boundary-layer height by regulating the surface energy distribution. Finally, it is worth noting that the surface pressure can affect the development of the nocturnal boundary layer in the northeast of China by influencing the ascending and descending movements of the air flow.