The invention discloses purple yam essence, and a preparation method and application thereof. The purple yam essence is prepared from 2,3,5-trimethyl pyrazine, 2,3-dimethylpyrazine, dimethyl sulfide, butanedione, 3-hydroxy-2-butanone, 3-methylthiopropanal, 2-acetylpyrazine, 3-methylthio-propanol, butyryl butyl lactate, gamma-heptalactone, gamma-caprylolactone, ethyl maltol, maltol, anisic aldehyde, gamma-nonalactone, ethyl myristate, gamma-decalactone, delta-decalactone, mercaptan, delta-dodecalactone, ethyl vanillin, vanillin, trans-2-ethoxy-5-phenol and vanilla bean tincture are used as the main raw materials. the purple yam essence is prepared by adding all the raw materials into a container and uniformly agitating and mixing to obtain the purple yam essence. According to the purple yam essence, the raw materials are rich in source, so that the purple yam essence is coordinated and soft in aroma, has the natural featured aroma of prepared henry steudnera, and is rich in aroma, long in lasting time and stable. The purple yam essence can be used for adding the aroma of cakes, ice cream, milk products, drink and other products.