When highly weathered weak rock used to fill embankment, compaction character and wetting deformation character are major evaluation indexes. Based on California Bearing Ratio (CBR) test for highly weathered weak rock under different compaction degree, it was shown that the value of CBR increased as the increase of compaction degree. By means of dry-wet double curve parallel tests and wetting deformation experiments of different compaction degree of highly weathered weak rock under complex stress, the results indicated that when the degree of compaction is 90%, under rather high deviatoric stress, wetting can not only generate high additional axial deformation, but also cause fairly high additional volumetric strain and partial strain. And wetting cause shear intensity of soil reducing. So increasing the compactions of subgrade filling is the important way to reduce wetting deformation and to enhance slope stability of subgrade.