Indoor frost heaving and thaw settlement tests were carried out for weak expansive soil in Huainan under the condition of different moisture content、cold junction temperature,etc,by using self-made frost-heaving and thawing-settlement test system. The results show that the frost heaving ratio increases as the moisture content、cold junction temperature and dry density rise,but reduces with the raise of saltbearing content. The relationship between frost heaving ratio and time can be described by exponential function:y=a(1-exp(-bt)) .The analysis on temperature and moisture variation law indicates that the more distant from cold junction, the slower the cooling rate is,and the time arriving at stable state becomes longer. The frost depth increases with the reduction of temperature, and coincides with development of temperature field.For the moisture migration during freezing process,the moisture content in the freezing area is greater than initial moisture content,and it is less in unfreezing area.The moisture content reaches the maximum in the vicinity of frozen fringe,where segregation ice interlayer forms owing to the water congregation. Besides,the results of thaw-settlement tests show that the thaw settlement is magnified when the moisture content goes up and temperature cuts down.The coefficient of thaw settlement and volume compression which provides parameters for frozen soil settlement calculation is determined with thaw settlement amount under different loads.