Abstract: The soil temperature characteristics from soil surface to 20 cm depth are investigated using data measured daily at four climatological observations,three stands and an open field of the located station during the period of 1992～1998.This study considered the index terms in the monthly mean,annual range,monthtomonth difference,amplitude of the monthly variation etc.In addition,according to the distribution of the vertical temperature gradient of the soil in every month,which indicates the direction of the thermal current in the soil.The depth of the layer of the annual constant temperature of the soil was computed with the formula of the thermal wave of the soil,the results showed that the soil depths of the variable temperature inside the stands were deeper 2～5 m than those in the open field.