Abstract: Based on conventional meteorological observation data and PM_2.5 concentration data, the characteristics and causes of persistent fog and haze weather occurring from January 10 to 14, 2019, in Dongli District of Tianjin were analyzed. The results show that the fog and haze weather has obvious phase characteristics. The general circulation, including upper-level straight stable westerly circulation, middle-level warm ridge, and weakened surface pressure, provides favorable synoptic conditions for the fog and haze weather. Visibility is more susceptible to relative humidity during light fog and haze stages, while at the fog stage, it is more susceptible to wind speed. PM_2.5 concentration and surface meteorological elements are closely related. PM_2.5 concentration is negatively correlated with visibility and wind speed and positively correlated with relative humidity. When other meteorological conditions are stable and the concentration of pollutants is high in the surrounding areas, the change of wind direction near the ground plays a key role in the occurrence of fog and haze in this regiony.