Objective:To analyze the medication law of external application of TCM in the treatment of psoriasis vulgaris (PV) by using data mining method.Methods:Clinical controlled trial literature about external application of TCM in the treatment of PV was retrieved from CNKI, VIP, WanFang, SinoMed, PubMed and Cochrane Library from the establishment of the databases to May 23, 2022. Prescriptions were extracted after screening. TCM inheritance computing platform V3.0 was used to analyze the property, taste, meridian, efficacy, use frequency, common medicinal pairs and the core combinations.Results:A total 186 prescriptions were included, involving 190 kinds of Chinese materia medica. The medicines were mostly bitter and cold in property and taste, mainly belonging to the liver and heart meridians. Heat-clearing drugs were mainly used, followed by blood circulation-activating and stasis-eliminating medicines, and tonic medicines. The ten most frequently used medicines were Sophorae Flavescentis Radix, Dictamni Cortex, Phellodendri Chinensis Cortex, Kochiae Fructus, Angelicae Sinensis Radix, Salviea Miltiorrhizae Radix et Rhizoma, Poria, Rehmannine Radix, and Arnebiae Radix; the 3 commonly used medicinal pairs were Sophorae Flavescentis Radix- Dictamni Cortex, Sophorae Flavescentis Radix- Cnidii Fructus, and Sophorae Flavescentis Radix- Kochiae Fructus; 4 combinations were obtained through evolution. Conclusions:External application of TCM for the treatment of PV is around the core pathogenesis of "heat toxin", mainly treating from the blood, including cooling blood and detoxifcation, activating blood circulation and removing stasis, nourishing the blood and moistening dryness. Clearing heat and drying dampness, dispelling wind and relieving itching are also valued. The treating thoughts can provide some references for clinical treatment.