Objective: This study aimed to study the effect of matcha on lipid oxidation during the storage of coix seed. Methods: The fresh coix seeds were used as raw material and treated with matcha tea powder in different doses. The changes in water content, fatty acid value, peroxidation value, malondialdehyde content, total number of colonies and key enzyme of lipid oxidation were determined during the storage of coix seeds. Results: The treatment with different doses of matcha powder could inhibit the increase of fatty acid value, peroxide value, malondialdehyde content, lipase, and lipoxygenase activities, and reduce water consumption and microbial growth during storage of coix seeds. The preservation effect of matcha on coix seeds was dose-dependent to a certain extent, but the difference in the preservation effect of adding matcha tea powder with a mass fraction of 0.05% and 0.08% was small. After 4 months of storage, compared with the self-sealing bags group, the fatty acid value, peroxide value and malondialdehyde content of coix seeds in the treatment group with the addition of 0.05% matcha powder were decreased by 31.6%, 30.77% and 44.83%, respectively. The activities of lipase and lipoxygenase decreased by 23.05% and 28.74%, respectively, and the composition and content of free fatty acids were more similar to those of fresh coix seeds. Conclusion: Matcha could effectively inhibit lipid oxidation during storage of coix seeds and extended shelf life.