Abstract: Based on the precipitation, cloud cover, and fog observational dataset from five meteorological stations in Tianjin region, the facts of climate change in Tianjin during the last 50 years are analyzed. The results indicate that the urbanization effect on the local climate change in Tianjin is increasing significantly, and the changes of cloud cover, precipitation, and fog have been influenced by aerosol pollution by human activities. It shows that the low cloud cover is increasing, the decrease in the drizzle days is slowing down, and the foggy days in winter have increased dramatically since the 1980s, especially in the areas of obvious urbanization. Whereas the change of the precipitation over the past 50 years in Tianjin region also includes the influence of the largescale background condition changes.