Abstract: Based on daily data observed at conventional meteorological stations during the period from 1958 to 2013, we developed different criteria for freezing processes selection in the North and South of china according to the impact of freezing rain and snow on the high way traffic operation. Then we set up a composite indicator called “freezing intensity” based on the grey correlation degree analysis, and taking the freezing duration, the rainfall duration, the average precipitation and the average daily temperature in each freezing process as the factors. The test results show that the composite indicator “freezing intensity”may describe the spatial-temporal variation of the freezing weather quit well. What’s more, it can reflect the extent of impact of freezing weather on the highway traffic operation.