The Jingtai Irrigation Zone with an acreage of 200km² is located alongside the upper reaches of the Yellow River,in Gansu Province,Northwest China.Under the control of arid and semiarid climate,besides the influence of strong evaporation it is subject to strong effects of seasonally freezing and thawing processes as well.The uneven distribution of salt and water makes the freezing point of soil different from one depth layer to another.It is found based on the field investigation that the frozen period of salinized soil was shorter and the maximum frozen depth shallower.The starting position of soil freezing is from a certain depth below the soil surface other than from the soil Surface.The freezing characteristic makes the salt-water-heat dynamic more complex due to two freezing fronts occurring during freezing.