Abstract: On the afternoon of 14 February 2020, an extremely rare large hail event occurred in Enshi, Yichang, located southwestern Hubei Province, producing hailstones larger than 5 cm in diameter along with numerous smaller hailstones. Based on observations from automatic weather stations, radar and satellite, and the ECMWF ERA5 reanalysis data, this study analyzes environmental characteristics, triggering mechanisms, the storm structure, and causes of large hails in this hailstorm event. Results show that before convective initiation, the 0—6 km vertical wind shear reached 19 m/s, yet the Convective Available Potential Energy (CAPE) was only 438 J/kg, indicating a rare large hail event in a High-Shear Low-CAPE (HSLC) environment. At 850 hPa, the peripheral shear of the southwestern vortex led to strong convergence between the warm-moist low-level southeasterlies and cold-dry northeasterlies in the mountainous area of northern Enshi. Combined with orographic lifting, this circulation pattern resulted in the development of two convective cells into supercells (hereafter referred to as cell A and cell B). Cell A is an isolated classical supercell, while cell B is an embedded supercell within a multicell storm, and both produced large hailstones. Estimates of updrafts in the two supercells based on divergence and perturbation pressure methods show that after the mesocyclones intensified, the dynamic perturbation pressure gradient force in the mid-lower levels of the storms contributed more significantly to the updrafts than in the mid-upper levels. The maximum updraft occurred near 6—7 km above the ground level. In the high-shear environment, the accelerations of both linear and nonlinear dynamic vertical perturbation pressure gradients were equally important for storm development. In the early stage of the storm, the mesocyclone was weak, the contribution of the nonlinear term was small, and the low-level updraft was dominated by the linear component. As the mesocyclone intensified, the nonlinear term became the dominant factor in the updraft. The mesocyclone prolonged the residence time of hail embryos in the region rich in supercooled water, allowing them to grow into large hailstones. More importantly, the perturbation pressure generated by the mesocyclone compensated for the insufficient buoyant vertical acceleration in the low-CAPE environment, enhancing the updraft. This, in turn, enabled the updraft to support larger hailstones and further extended their residence time.