The study will focus on the frost heave microdeformation and control mechanism of the grading macadam of railway subgrade bed for high-speed railway in seasonal freezing regions. Combined with the influence of temperature, moisture and character of loading, the hydrothermal stability of high compactness degree grading macadam and caused frost heave microdeformation will be examined by a serial of laboratory experiments.This kind of microdeformation has a crucial impact on the operation of high-speed railway.Research by freeze-thaw tests,microscopic observations and model tests, the microdeformation mechanism of grading macadam due to the different temperature variation, water transference and loads will be analysed. Then the corresponding models will be established.This study will have significant importance for highspeed railway or highway construction in freezing regions, it is actually a new direction in frozen soil engineering study.