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Betulin and oleanolic acids (pentacyclic triterpenoid) have broad pharmacological activities and can be potentially used for the development of anti-cancer and anti-AIDS drugs.In this study, regulation effectson triterpenoid synthesis and their distribution and variation pattern of temporal and spatial in the growth process of white birch saplings were studied through the regulation of various environmental factors.We also determined the expression of 4 OSC genes involved in the triterpenoid synthesis pathways by real time RT-PCR.The research laid bases for seting up the cultivation technology of high efficient accumulation and metabolic regulation study of the triterpenoid substances of white birch.During the growing season (May to October), the accumulation peak of secondary metabolites in stem bark was from the end of July to late August.Low nitrogen could promote accumulation of oleanolic acid in the root skin and leaf, while the high nitrogen was more beneficial to the accumulation of oleanolic acid and betulin.MeJA spraying (50~100 μm) could effectively promote the triterpenoids accumulation in bark, and the most content produced by this treatment was at the end of July.Medium (water 35%) and mild drought stress (water 50%) can promote accumulation of the oleanolic acid and betulin in stem bark, respectively, while severe deficiencies of water (water 15%) inhibit synthesis of triterpenoids.During the growing season, the gene expression of BPW and BPY in leaves was the lowest, while the highest in stem cambium from end of July to end of September.The expression of BPY gene was high in root from end of July to end of October, the BPW gene showed the highest expression in root in August, and the highest expression level of BPX arose at the end of august, but its product was comparatively low.The mRNA of triterpenoid genes (BPW, BPX and BPY) took the similar accumulation and distribution to triterpenoid constitutes, and both them were markedly regulated by the season.