Abstract: The complex ingredient of red beds and some kinds of rock contained in red beds have the property of slaking which leads red beds material to the engineering properties of great complex and instability. Test data of chemical ingredients, physical properties, and durability of slaking on the rocks from red beds show that the properties of rocks composed of red beds are greatly different with each other. As those rocks mixed in site, it is difficut to treat them separately. But experiment on the slaked material from the red beds rocks shows that the properties of those material are stable. By analyzing of the experimental data of the material slaked entirely, the relation formulas between road engineering property indexes and void ratio index were put forward here. Experiments show the physical and mechanical indexes of those material with compacting factor of 95% can reach the requirement of embankment. Result of the applications on a expressway combined with the experimental data in situ and survey result after construction show that red beds material can be used as embankment filling material after slaking. By using proper construction method, construction duration can be greatly shortened.