Abstract: Forests can improve climate and regulate micro-environment. The study of forest micro-climate is of great significance to reveal forest ecosystem function and evaluate the benefits of forest ecological environment. With broadleaved Korean pine forest in Changbai Mountain as test material, the diurnal and seasonal variations of the mean, maximum and minimum temperature, relative humidity and surface soil temperature were analyzed based on the meteorological data of flux tower in the forest and nearby meteorological station in the open land from 2003 to 2014. The results showed that air temperature and relative humidity in the forest showed a unimodal U-shaped diurnal pattern, respectively. The diurnal range was 2.31 ℃ and 8.3% lower than that of the open land. The diurnal surface soil temperature tended to be a constant, indicating an alleviating effects of broadleaved Korean pine forest on the diurnal variation of temperature and moisture. The cooling effect was mainly observed in summer, while the warming effect was significant in winter. The air and soil temperatures in forest in summer were 1.30 and 3.91 ℃ lower than those in the open land, and were 2.06 and 5.44 ℃ higher than those in the open land in winter. Forest regulated the maximum and minimum temperatures significantly. On the season scale, the maximum air and soil temperature in forest decreased by 1.80 and 5.45 ℃ in summer, while the minimum air and soil temperature increased by 3.69 and 7.92 ℃ in winter. On the annual scale, the maximum air and soil temperature in forest were 1.60 and 4.99 ℃ lower than those in the open land, and the minimum air and soil temperature were 1.12 and 8.82 ℃ higher than those in the open land, respectively. The regulating effects of forests on soil temperature was stronger than that on air temperature. Forests mainly warmed the air and soil temperature at cold condition.