Abstract: Through the one-dimensional frost heaving test in open system of silty clay,taken from Beijing to Baotou and Baotou to Lanzhou railway subgrade,the freezing and frost heaving behavior of the soil were analyzed,taking into the consideration of the influence of the cooling temperatures.The following conclusions can be drawn:(1)Silty clay was a kind of soil which was sensitive to frost,soil and the water supplement were the main factors to cause frost damages at that area.(2) Cooling temperature had great influence on the course of freezing and frost of the soil,the depth of freezing increased with the descending of the cooling temperature,while frost heaving decreased with the cooling temperature descending.(3)An inversely proportion relationship existed between the frost heaving ratio and the freezing rate,at the very small freezing rate,the depth of freezing almost had no increase,but the larger frost heaving rate was observed.