Using several indexes of urbanization, the relationship between urbanization and Urban Heat Island effect (UHI) from 1980 to 2009 in Taiyuan is studied. It is discovered that urbanization was the main reason for the formation and reinforcement of UHI. The conclusions are as following: (1) In recent 30 years, the tendency of temperature in Taiyuan was 090 ℃ per 10 years, 051 ℃ per 10 years in the suburbs; UHI also increased, and the tendency of UHI intensity was 039 ℃ per 10 years. (2) There was a significantly positive correlation between urbanization and UHI for all types of indexes. (3) There is a linear correlation between the urban rural temperature difference and the logarithm of total population logarithm, and the long term correlative coefficient reached to 081 (4) The natural logarithm of housing construction area and the difference were linearly correlated, and the long term correlative coefficient reached to 085