Abstract： Objective： To analyse the medication and compatibility rules of Chinese medicine cosmetic external prescriptions by data mining technology. Method：The Database of Chinese Medicine Classic Prescriptions established by the Institute of Information on Traditional Chinese Medicine was applied to retrieve external prescriptions related to Chinese medicine cosmetology for whitening，freckle removal，anti-wrinkle and treatment of acne；plug-in unit of data mining was used to count the occurrence frequency of single herbs used in external prescriptions with four kinds of effects respectively； the association rule is applied to analyze the compatibility rules of medicines. Results： The statistical results of occurrence frequency of single herbs showed that Radix Angelicae Dahuricae，Rhizoma Bletillae and Radix Ampelopsis were frequently used in the four kinds of cosmetic external prescriptions. The high- frequency single herbs for whitening included Rhizoma Typhonii，Rhizoma Atractylodis Macrocephalae，Poria，etc.；the high- frequency single herbs for freckle removal included Flos Caryophylli， Lithargyrum， Radix Saposhnikoviae， etc.； the high- frequency single herbs for anti- wrinkle included Semen Armeniacae Amarum，Radix et Rhizoma Nardostachyos，Radix et Rhizoma Asari，etc.；the high- frequency single herbs for the treatment of acne included Calomelas， Semen Pharbitidis， Sulphur， etc. The analysis of association rules showed that the high- importance drug combinations for whitening included Rhizoma Bletillae- Radix Ampelopsis，Rhizoma Atractylodis Macrocephalae-Lignum Santali Albi，etc.；the high-importance drug combinations for freckle removal included Radix Angelicae Dahuricae- Semen Pharbitidis， Rhizoma Bletillae- Radix Ampelopsis， etc.； the high- importance drug combinations for anti- wrinkle included Radix et Rhizoma Nardostachyos- Fructus Broussonetiae， Poria- Rhizoma Chuanxiong， etc.； the high- importance drug combinations for the treatment of acne included Rhizoma Typhonii- Radix Ampelopsis， Semen Armeniacae Amarum- Sulphur， etc. Conclusion： The external prescriptions are mainly used on the affected areas in the form of fumigation， wet compressing， smearing， bath， etc. The medicines used in external prescriptions for whitening，freckle removal，anti-wrinkle and treatment of acne have similarities and differences；the main medicines are those for whitening， moistening dryness， clearing heat and dispelling wind， accompanied by those for aroma，detoxicating and destroying parasites，invigorating blood，resolving putridity and regenerating tissue.