On 14 June 2016, a longlife supercell storm produced a wide range of hailfall and thunderstorm gale in Shandong Province. Based on the conventional observation, mesoscale automatic station, Doppler weather radar and wind profile radar data, the weather background and radar observation characteristics are analyzed, and the maintenance mechanisms are discussed. The results show that under the background of a cold vortex in North China and the environment conditions of strong deep vertical wind shear and medium convection available potential energy, the surface mesoscale convergence center triggered the strong convective storm. In the maintenance stage, there was an inflow entrance of warm and moist air on the left front of the storm at the lower level. The vertical structure showed the structural characteristics of the classical supercell, and a deep and strong mesocyclone developed, with the biggest vertical vorticity basically being above 1×10-2s-1 and each rapid increase and decrease of the central height accompanied by the occurrence of a single hail event. The supercell storm moved along the mesoscale convergence line at the development and maintenance stages, and there formed a strong convergence updraft in front of the storm because the ground cooling pool boundary expansion was balanced with the lowlevel vertical wind shear. The relative helicity of the storm was above 150 m2〖DK〗·s-2, which were the favorable conditions for the supercell storm to maintain a long time.