This study analyzes the “24·7” extremely heavy rainstorm event in southern Shandong using conventional observations, ERA5 reanalysis and GDAS data. The main conclusions are as follows. (1) The orientation of the rain belt is determined by the spatial configuration of the convergence zones ahead of the 700-hPa low-level jet (LLJ), 850-hPa LLJ and 925-hPa super LLJ (SLLJ). In the first two stages, the convergence zones at various levels are oriented east-west, resulting in an east-west oriented rain belt. In the third stage, the intrusion of cold air shifts the convergence zone to a north-south orientation, causing a corresponding shift in the rain belt. During the initial nocturnal intensification of the jets, the northern boundary of the 925-hPa wind speed v_{925 hPa} ≥12 m·s^-1 corresponds to the southern boundary of the precipitation, while the northern boundary of the 850-hPa wind speed v_{850 hPa} ≥12 m·s^-1 corresponds to the northern boundary of the precipitation. After the southward advance of cold air in the third stage, the southern boundary of the precipitation is still defined by the 925-hPa SLLJ, whereas the northern boundary coincides with the top of the 850-hPa LLJ and the convergence zone near the shear line. (2) The diurnal variation in the precipitation intensity is primarily dominated by the convergence associated with the 850-hPa LLJ and 925-hPa SLLJ, exhibiting synchronous characteristics of “enhancement in the night and weakening in the afternoon”. The 700-hPa LLJ provides steady convergence and transfer of water vapor. Correlation analysis indicates that the regional average precipitation rate is significantly positively correlated with the intensity of jets at all levels, while the regional maximum precipitation rate has the closest relationship with the intensities of the 850-hPa LLJ and 925-hPa SLLJ. (3) The transfer of water vapor exhibits diurnal variations closely linked to the activity of the 850-hPa LLJ and 925-hPa SLLJ, with the diurnal variation in the water vapor flux intensity at 850 hPa and 925 hPa aligning well with the evolution of precipitation intensity. The water vapor flux at 700 hPa remains consistently positive, providing stable water vapor support for the maintenance of the rainstorm. (4) The sources of water vapor show significant stage-dependent differences. In the first two stages, the water vapor is primarily from the South China Sea and the Bay of Bengal, transported to southern Shandong by LLJs for convergence. In the third stage, the southward intrusion of cold air brings a northern air mass, which has been moisturized over the Bohai Sea. This air mass converges with the warm, moist air from the South China Sea over southern Shandong, forming a “northern-southern water vapor convergence” pattern. This significantly enhances the intensity of water vapor convergence and serves as a key condition for the precipitation to reach its peak in the third stage.