Abstract: The differences of microphysical characteristics and snow-to-liquid ratios for two rain and snow processes in Beijing during Winter Olympics in 2022 and the same period in 2020 were analyzed based on Parsivel data, densely artificial snow-depth measurements, and microscopic snowflake shape observations. The results show: (1) The average particle spectrum showed a unimodal pattern, with the highest and lowest peak number concentrations attributed to the snowflake spectrum and raindrop spectrum, respectively. During the snowfall process, the peak number concentration of plate- or column-like ice crystals was higher than that of dendritic snowflakes. (2) An average falling speed of particles below 2 m s⁻¹ could be used as an indicator of phase transfer. The average falling speed of dry snow particles was less than 1 m s⁻¹. (3) The ambient air temperature during the rain-to-snow process was high on 13 and 14 February 2020. The growth of snowflakes in the sleet stage was mainly due to the riming process. With a decrease in the temperature at lower levels and a significant increase in humidity in the layer with temperatures from −18°C to −12°C, the precipitation process changed to snowfall, and the riming process continued to exist. Under the joint action of riming and adhesive aggregation processes, the maximum crystal diameter reached 19 mm, but the snow-to-liquid ratio was low (0.6 cm mm⁻¹). (4) In the snowfall process during the Beijing Winter Olympics, the temperature was lower in the low-level cloud region (between −18°C and −12°C), and the falling velocity was close to the classical curve of the unrimed ice crystals; therefore, the snowflakes were all unrimed. The combined action of sublimation, the Bergeron process, and hook aggregation caused a growth in the particle diameter to 11 mm. However, a change in snowflake shape to plate- or column-like geometries was observed at the Shougang Big Air Venue during the Beijing Winter Olympics, resulting in an increase in the number concentration and a reduction in the particle spectrum width, with a corresponding sharp reduction in the SLR.