Based on the macro and micro observation data, the types and main mechanisms of formation, development, weakening, and dissipation of 4 burst reinforcement winter fog events that occurred in Jinan are analyzed, the microphysical characteristics in the stages of formation, development, mature, and weakening as well as in the course of burst reinforcement are studied, and the causes of burst reinforcement are discussed in this paper. The results are as follows. 1) The air cooling caused by the upward long-wave radiation at night and the invasion of cold air is the key to the formation and development of winter fog in Jinan, and the dissipation or weakening of winter fog owes to the decrease of relative humidity near the surface layer caused by the invasion of dry and cold air or the heating up of solar radiation after sunrise. 2) In the formation stage, the process of nucleation and condensation growth starts but is not active, the collision-coalescence process is very weak, and there are mainly no or occasional collision-coalescence process; in the development stage, the microphysical processes such as nucleation and condensation growth start to be active, the collision-coalescence process starts, and the number of big droplets increases; in the mature stage, the nucleation, condensation, and the collision-coalescence growth become very active, all the microphysical quantities reach their maximum, and the spectrum is the widest; in the weakening stage, the nucleation and condensation growth are weakened, the collision-coalescence growth becomes weak until it disappears, the droplets are evaporated, and the visibility increases. 3) The macrophysical characteristics of burst reinforcement are the increase of extreme wind speed and relative humidity and the decrease of air temperature and water vapor pressure, while the microphysical characteristics are the sharp increase of microphysical quantities such as number concentration and liquid water content and the abrupt change of spectrum distribution from one-peak to multi-peak structure. 4) The increase of relative humidity is mainly caused by the air cooling, and the decrease of water vapor pressure is mainly related to the active condensation growth; the burst reinforcement of winter fog in Jinan is directly caused by the air cooling, and the humidification caused by the weak transportation of water vapor promotes the reinforcement to some extent.