The evolution and structure of a supercell, which occurred from afternoon till night on 14 June 2016 in central Shandong Province, is analyzed based on the Doppler weather radar data and conventional observation data in Jinan, Binzhou, and Weifang. The main results are as follows. The supercell storm occurred in a favorable environment of high convective available potential energy (CAPE) and strong vertical wind shear. Its evolution can be divided into two phases, the classic supercell phase and high-precipitation (HP) supercell phase. The classic supercell, with distinct features, evolved rapidly from the initial ordinary cells. The HP supercell formed through the mergers of the previous classic supercell and smaller ordinary cells originated from its rear-flank downdrafts. During the mergers, the rotation is intensified and tornado-like small-scale vortices are generated, leading to gales on the ground and large hailstones.