Abstract:Bretschneidera sinensis Hemsl., a tertiary relict tree endemic in China, was listed in National Key Protected Wild Plants (Class I) as a rare species. It is significant for the studies on phylogeny, paleogeography and paleoclimate of angiosperm. It was discovered that natural regeneration of the population was quite difficult and one of the key causes is the high death rate of its annual regenerated seedlings. Site experimentation was conducted to monitor the growth status of annual regenerated seedlings in different habitats, in order to discuss the common death causes of the seedlings and to study the effects of soil pH and different shade treatments on the growth of seedlings, also the effective conservation measures were advised to promote its natural regeneration. Results indicated that, as a perennial tree, the root tip of B. sinensis has no root hair differentiated, so it needed special habitats with enough nutrition and would be caused death easily by many lethal factors. The main death causes of the seedlings consisted of 3 aspects: the decay of root system because of poor permeability of soil, water shortage by drought stress in summer, predation risk by cabbage caterpillar because of the myrosin cell in its stem and leaf which is the necessary development site for the pest, respectively. The seedlings were adapt to weak acidic soil (pH=5.0-6.5), so the species only distributed in the south area of Changjiang river according to the changing rule of the soil properties in China. Also the diverse light intensity differed significantly in the survival rates in hot summer and biomass accumulation of annual regenerated seedlings. Results of light control treatment showed that the natural sunlight would cause the death of seedlings seriously, while severely weak shade conditions would inhibit the biomass accumulation. Only moderate shade treatment was suitable to the growth of seedlings, and the biomass indexes (plant height, basal diameter, number of leaves and number of branches) and the survival rate were all highest under natural shade treatment. Accordingly, suitable water and fertilizer management and moderate shade treatment were recommended to be utilized on the annual regenerated seedlings of B. sinensis as conservation strategies, including using shading net by one layer in the field or natural shade under the forest with middle canopy density.