Multi-source observation data, such as national meteorological observation station, wind profile radar, X-band dual-polarization phased array radar, and ECMWF (European Centre for Medium-Range Weather Forecasts) Reanalysis v5 (ERA5) are used to analyze the characteristics and causes of the large-scale snowstorm (partially severe snowstorm) process in Shandong from 13 to 14 December 2023 (“12·14” snowstorm for short), which is compared with the extreme snowstorm process on 7 November 2021 (“11·7” snowstorm for short) to study the reasons for differences in snowfall amount and snow-to-liquid ratio. The results are as follows. (1) The synoptic situation of typical warm advection type is a favorable circulation background for extreme snowstorm. The low-level shear line and wind speed convergence are overlapped in the northwest of Shandong Province, forming a strong and persistent ascending motion. (2) The low-level jet is abnormally strong, and the precipitation intensity is not only related to the intensity of the low-level jet, but also to its thickness. When the intensity of the low-level jet maintains at the height of 3.0 km, the lower the height of the 10 m·s^-1 wind speed, the greater the snowfall intensity. (3) The duration of specific humidity exceeding 4 g·kg^-1 at 700 hPa and 3 g·kg^-1 at 850 hPa is both over 10 h, providing sufficient water vapor for the extreme snowstorm process. The 850-hPa specific humidity and specific humidity advection of the “11·7” snowstorm are much higher than those of the “12·14” snowstorm, which is one of the factors contributing to the maximum cumulative snowfall of the “11·7” snowstorm being greater than that of the “12·14” snowstorm. (4) For the “12·14” snowstorm, the vertical motion is vigorous, the maximum ascending velocity is located at the forefront of the unstable layer, and the temperature is between -20 and -10 ℃, which are all conducive to the growth of dendritic ice crystals and high snowfall efficiency. The temperature of the entire troposphere is below 0 ℃, and the snowflakes do not melt during the falling process, so the snow-to-liquid ratio is high, and the depth of snow is large. For the “11·7” snowstorm, the center of the maximum ascending motion during the early stage is lower, forming more columnar ice crystals that melt when passing through the warm layer. Therefore, the snow-to-liquid ratio is lower and its snow depth is smaller than that of the “12·14” snowstorm.