The invention provides a nano composition with hair loss preventing, hair growing, hair fixing and hair blackening functions as well as a preparation method and application thereof, and relates to thetechnical field of cosmetics with special functions. The nano composition comprises diaminopyrimidine oxide, pyrrolidinyl diaminopyrimidine oxide, hair growing peptide, hair fixing peptide, hair blackening peptide, a cell penetrating agent, vitamin E, polydiethylene glycol succinate, phospholipid, cholesterol, polyhydric alcohol and water. The nano composition is good in transdermal performance,improves the adsorption capacity of a preparation on scalp, deeply permeates into hair follicles, can be retained in the hair follicles for a long time, can be maintained at an effective concentrationfor a long time, improves the bioavailability, reduces the use amount of active ingredients, and enables low-content and anti-hair-loss active matter to play an excellent anti-hair-loss effect.