Abstract: In November 2018 and 2019, rhizomes of Polygonatum cyrtonema ‘Lijing No. 1’ were planted open air, under different canopy density of Phyllostachys edulis forest, Cunninghamia lanceolata stand and Torreya grandis ‘Merrillii’ seedling stand with similar site condition in Songyang and Jingning, Zhejiang province. In November 2022, rhizomes were harvested for determination of phenotypes and yield. The polysaccharides, saponins, phenols and flavonoids were measured, and antioxidant activities were assessed by DPPH, ABTS and FRAP. The result demonstrated that crown density was the most important factor affecting the yield of rhizome. The dry weight of single 4-year plant under forest with 50% of crown density could reached 100 g, which had no significant difference of that in open-air ones. The yield of P. cyrtonema cultivated under forest with 50% of crown density decreased significantly compared with that in open-air ones. The yield of 4-year P. cyrtonema under different cultivation site increased 150% more than that of 3-year ones. The contents of extract and polysaccharide from P. cyrtonema cultivated under forest with lower than 50% of crown density and open air increased significantly. The contents of total saponins, total phenols and total flavonoids from P. cyrtonema cultivated forest with more than 70% of crown density were higher, and the antioxidant capacity was significantly increased.