In order to study the frost heaving performance of subgrade in seasonal frozen area, the scale model test was carried out based on the practical engineering.Unidirectional freezing-thawing test was carried out under open conditions to analyze the temperature distribution and frost heave characteristics in the two freezing-thawing cycles under different temperature gradients.The frost heaving equipment developed by ourselves can meet many test indexes such as deformation and temperature.The results show that the freezing rate decreases with the increase of time and has certain fluctuation.Freezing depth increases with the increase of freezing negative temperature, and at -15℃, the maximum freezing depth reaches 39cm.Based on the analysis of the relationship between freezing depth and time, the formula of freezing depth prediction is put forward.It was found in the relationship between different cold end temperature and frost heave, when the freezing negative temperature was -10℃, the soil reached the maximum frost heave.