Soil temperature (SoT) is one of the important climate elements for the land-atmosphere interactions. In this study, the climatic characteristics and trends of SoT were analyzed at nine locations for the period of 1966 to 2020. In addition, effect of precipitation on the interannual variations of SoT was also addressed. The monthly average of the SoT shows seasonal and interannual variations regardless of location. While there are some differences depending on the location and depth, the interannual variations of SoT occur more strongly at the shallow layer during summer comparatively other seasons. The strong negative correlation between SoT and precipitation of summer shows that the large interannual variations of SoT in summer is closely related to the strong interannual variations of precipitation of same season. According to the depth the range of SoT is larger in winter and summer and smaller in spring and autumn. Generally, air temperature and SoTs are increasing due to global warming. However, the increasing trend varies and depends on the location and depth of the study area. Most of investigation stations are revealed a strong increasing trend, particularly, at the shallow layer during summer season.