To improve snowfall forecast accuracy and aviation meteorological services at Lhasa Airport, by employing the improved Jenkinson-Collison (J-C) circulation type classification method, this paper classifies and diagnoses 56 snowfall events that occurred during 2013—2020 at Lhasa Airport. The results are that, with the improved method, a classification success rate of 92.9% is achieved, and three types, i.e., the cyclonic type (12.5%), low-pressure trough type (42.9%) and westerly advection type (37.5%) of snowfall events are identified. There are only 7.1% of snowfall events remaining unclassified-significantly lower than that by the traditional method. The characteristics of the three identified circulation types are significantly different. The cyclonic type, corresponding to plateau vortices, features the strongest dynamics and water vapor conditions, with the most average snowfall (3.4 mm) and longest duration (358 min). The low-pressure trough type, influenced by the southern branch trough, shows the most unstable atmospheric stratification but relatively weak dynamics and water vapor, resulting in the lowest mean snowfall (1.2 mm) and shortest duration (170 min). The westerly advection type, dominated by warm ridges and upper-level jets, has the most stable atmospheric stratification, with a “low-level convergence and upper-level divergence” moisture structure. Its intermediate snowfall indicators lie between those of the other two types, that is, the average snowfall is 1.8 mm and the duration is 280 min. These findings could provide a scientific basis for refined snowfall forecasting and help improve the aviation meteorological services at Lhasa Airport.