The invention provides a matrine percutaneous administration new dosage form, namely an o / w type matrine percutaneous absorption microemulsion, and a preparation method thereof. The o / w type matrine percutaneous absorption microemulsion comprises matrine, a surfactant, a cosurfactant, an oil phase and water, and is characterized in that the particle diameter range of the matrine microemulsion is 20-70 cm, and the mean particle size is 31.2 nm. The formula of the o / w type matrine percutaneous absorption microemulsion comprises the following components in percentage by weight: 7% of matrine, 23% of the surfactant, 15% of the cosurfactant, 4.5% of the oil phase, and 0.5% of the water. The o / w type matrine percutaneous absorption microemulsion provided by the invention has the advantage of overcoming the defects of the available matrine injection and matrine oral preparation, such as rapid in vivo release, instable blood concentration and low bioavailability; and the microemulsion permeates skin to enter blood with zero-order kinetics, and has improved bioavailability compared with the oral preparation, so as to provide convenience for infants and chronic disease patients needing long-term administration. The microemulsion also has a distinct effect on inhibiting hypertrophic scar of rabbit ears, and is hopeful to become a candidate medicament for treating hypertrophic scar.