The monthly, annual, and inter-decade variations of heat island effect in inner and outer suburbs of Shenyang and their relationships with urbanization were analyzed, based on the air temperature data from 1961 to 2008. It was indicated that the monthly and annual heat island effect was higher in inner suburb than in outer suburb, and decreased from inner suburb to outer suburb. The variation trend of monthly heat island effect in inner and outer suburbs was similar from March to November, but in contrary from December to next February, possibly due to the effects of heating in winter. The annual heat island effect in both inner and outer suburbs had an increasing trend before 2000 but a decreasing trend after 2000, and was significantly positively correlated with the green land area, population, and established construction area before 2000 (P < 0.05), but significantly negatively correlated with them after 2000 (P < 0.05), the correlation degree being 0.43, 0.52, and 0.26, respectively.