Abstract: There are 597 vascular species belonging to 299 genera of 89 families in Fenglin Nature Reserve, Heilongjiang Province of northeastern China. Amongst them, 560 species belonging to 275 genera and 76 families are seed plants, which respectively account for 34.15%, 45.30% and 73.79% of Heilongjiang seed plants; and account for 55.94%, 67.07% and 77.55% of Xiaoxing an Mountains seed plants; there are 8 species of endangered plants in the reserve, accounting for 57.14% and 80.00% of endangered plants in Heilongjiang Province and Xiaoxing an Mountains. Fenglin Nature Reserve is one of the main concentrated distribution area of endangered plants of Heilongjiang Province and Xiaoxing an Mountains, and it is also a typical plant area of Xiaoxing an Mountains flora. In seed plants, 41 families only have 1 genus each, 24 families only have 1 species each, and 164 genera only have 1 species each. There are 6 types of family distribution, mainly the cosmopolitan (4868%), the north temperate (25.00%) and the pan tropic (21.05%); there are 11 types of genera distribution, and the genera with temperate elements are dominated, which amount to 209 and account for 76.00%; there are 16 types of species distribution, besides the cosmopolitan and the species endemic to China, the number of genera with temperate elements is 415, accounting for 74.11% of the total in this reserve; the number of genera with subfrigidfrigid elements is 92, accounting for 16.43%; the number of genera with tropic elements is 34, accounting for 6.07% of the whole species in this reserve. Floristic characteristics show that species are very rich in this reserve, it also has complex geographic components, with the features of more families, more genera and less species, reflecting its old origin and conservation; genera with single and few species are plenty, showing richness and complexity of plant species diversity; it mostly belongs to the north temperate flora mixing with the plant floristic elements of subtropics, tropic, frigid and subfrigid zones, forming a mixture of the north and the south. This paper systematically analyzes the seed plant flora of Fenglin Nature Reserve, which can provide scientific foundation for protecting and making use of the seed plant flora of the nature reserve, and the way to manage the nature reserve availably.