In this work, the meridional variation of the thermal tropopause layer is investigated using high vertical resolution radiosonde measurements over China. A tropopause-based mean method is used to characterize the depth of the tropopause inversion layer (TIL), and a curve-fitting method to profiles of Brunt–Vaisala frequency is applied to identify the transition sharpness of the static stability in the tropopause transition layer (TTL). The eight radiosonde stations are grouped into four latitudinal bands at intervals of 7°. Analyses show that the tropopause at higher latitudes is much more likely to be sharp and have a strong TIL, while that at lower latitudes is dominated by a thick TTL.