Abstract: The paper aims to find the characteristics and cause of haze weather. We analyzed a rare haze weather process in Heilongjiang in November 2016 based on the observation data of surface and upper meteorological elements and pollutant composition and the method of the back trajectory. The results showed that: the meteorological conditions, including weak ground pressure field, weak trough of low and middle level, the increasing of temperature and humidity in low and middle troposphere, inversion conditions, and weak vorticity advection, were beneficial to air pollutant aggregation, the increase of concentration, and the visibility degradation, and caused the heavy haze weather, while the north airflow in front of cold high pressure was beneficial to haze dissipation. So, the weak meteorological condition is the important cause of the haze weather, and forecasting the weak weather condition is the key to forecast haze weather.