The study results showed that the composition of regenerated seedlings on limestone mountains in Than Sa - Phuong Hoang Nature Reserves is quite diverse. The number of seedlings range trom 42 to 72 species including 4-6 species that involved in composition formula. However, in this forest type the good quality seedlings accounted for very low proportion. The density of regeneration seedlings fluctuated trom 3187 to 7133 stems/ha, in which the natural seedlings accounted for 81.19 percent and the most of regeneration seedling is at the height of 50-100cm. The composition of regeneration seedlings involved in composition formula is mainly common species. There are only two rare species that involved in composition formula with the low proportion at two types (III and IV). In order to restore forest vegetation on limestone, the author should have several solutions in terms of restoration-oriented protection, forest management to reduce the negative impacts on forest ecosystems.