Abstract: To study the composition and antibacterial activity of Magnoliaceae plants, volatile oil was extracted by the steam distillation method from fresh leaves of Michelia hedyosperma grown in the Bawangling area of Hainan. After separation and purification, the chemical composition was analyzed by GC-MS and a total of 34 compounds were identified, accounting for 88.01% of the total composition. In addition to oxygen derivatives of monoterpenes and terpenes, most compounds belonged to sesquiterpenes. The components with higher abundance were Caryophyllene (11.442% ), Spathulenol (11.319% ), Carene (9.412% ), Aromadendrene (8.981%), Caryophyllene oxide (7.721%). In this study, the inhibitory effect of extracts from the leaves of M. hedyosperma on the growth of Escherichia coli, Staphylococcus aureus and Salmonella was studied using a filter paper diffusion method. The MIC for the above bacteria was 0.313, 0.625, and 0.625 g/mL, respectively. M. hedyosperma is a unique and endangered plant resource in Hainan. Under the background of building Hainan into an ecologically livable international tourism island, this study provides a valuable basis for conservation breeding and proliferation of M. hedyosperma. In addition, this study adds important information in the National Forest Germplasm Resource Platform regarding the composition and functions of the plant, and provides references for the development of new products in the fields of medicines, chemicals and foods by using the leaves of M. hedyosperma.