To understand the characteristics of horizontal visibility and correlation with air pollution in winter in Tianjin, the observational data of PM10 and PM25 mass concentrations, reactive gas bulk concentrations， and horizontal visibility in December of 2008 and January of 2009 are studied. The results indicate that the average horizontal visibility value was 1159 km, and the diurnal variation exhibited a singlepeak pattern with the maximum in the afternoon, which were affected strongly by aerosol mass concentrations and relative humidity. The occurrence frequency of haze approached 50%, which, being an important symbol of the poor air quality, resulted in low horizontal visibility. The observational data of PM10 and PM25 mass concentrations can be used to reflect the horizontal visibility approximately by using different nonlinear regression equations in winter. There was a negative correlation between horizontal visibility and aerosol mass concentration, and PM25 has greater effect on visibility than PM10 does. Under the high humidity condition, there existed better correlation between visibility and aerosol mass concentration.