Aromatherapy is a medical concept and method, which refers to the use of respiratory inhalation and skin penetration of natural plant essential oil into the human body, so as to play a physical disease treatment and mental illness treatment effect. Today, the concept and means of aromatherapy have been extended to the field of cosmetics, through the addition of appropriate amounts of natural plant essential oils in cosmetics to play a role in whitening skin, repairing skin, happy mood and other effects. This study focuses on the application effect and mechanism of aromatherapy in cosmetics, and explains in detail the practical effects of aromatherapy applied in cosmetics, such as whitening skin, repairing skin, reducing ultraviolet damage, controlling microbial growth, resisting aging, treating acne, etc. The medical mechanism of application of aromatherapy in cosmetics is analyzed and expounded, so as to explain the positive, remarkable medical effect and broad development prospect of application of aromatherapy in cosmetics.