There are 13 severe convective weather in Shandong in May 2020, including 8 hail processes occurring at 81 stations (65.9%) in 15 cities (93.8%) in total, with a maximum station-hail-hit number of 4 times. There are 10 thunderstorm gales above Beaufort scale 10 and 5 short-time heavy precipitation. The frequency, coverage, intensity, and severity of disasters have been rare over the last decade. The “5 ·17” convective weather process is the most intense, and its wide range of hail is very rare. The largest hail diameter is 4.5 cm, the maximum wind speed is 36.6 m ·s^-1 (Beaufort scale 12), and the maximum rainfall intensity is 56.9 mm ·h^-1. Based on ECMWF (European Centre for Medium-Range Weather Forecasts) Reanalysis v5 (ERA5) and data of intensive automatic meteorological observation stations, Doppler weather radar, and lightning location, the characteristics of severe convective weather in Shandong in May 2020 and the causes of frequent occurrence are analyzed. Taking the “5 ·17” severe convective weather process as an example, the characteristics of radar echoes and the vertical motion in the storm are analyzed. The results are shown below. (1) The stronger subtropical high not only favors the southwest warm moist airflow reaching Shandong, but also obstructs the westerly system, resulting in the forward trough getting intensified and maintaining over Shandong for a long time. The cold air carried by the northwest airflow in front of the 500-hPa enormously stronger warm ridge is superimposed over the 850-hPa unusually stronger warm temperature ridge, leading to an unstable atmospheric stratification over Shandong continuously. (2) Under the above favorable weather background, the water vapor over Shandong is abundant, CAPE (convective available potential energy) is large, the cyclonic convergence is strong at the junction of Hebei, Shandong, and Henan provinces, and there is a stable convergence line in the middle region of Shandong, which is easy to trigger severe convective weather, resulting in frequent severe convective weather in Shandong in May. (3) The highly organized convective storm, regional supercell groups, and a strong squall line with its length more than 500 km are the direct causes of “5 ·17” strong convection. The ascending velocity inside the storm reaches up to 28 m ·s^-1.