A preparation method for an antithyroid ointment for external application is provided. The ointment includes the following components by mass percentage: 0.01-10% gluco corticoid, 1-15% antithyroid drug, 0.1-30% percutaneous penetration enhancer, 10-30% oleaginous base and 4-40% water-soluble base. The method includes: mixing the glucocorticoid and a drug carrier material so as to evenly disperse the glucocorticoids on the drug carrier material to obtain a glucocorticoid component； placing and evenly mixing an antithyroid drug and other ingredients in distilled water, and heating to 80° C. and evenly mixing to obtain a water phase； melting an oleaginous base and a percutaneous penetration enhancer at 80° C. and evenly mixing to obtain an oil phase； maintaining at 80° C. and pouring the oil phase into the water phase, and evenly stirring； adding the glucocorticoid component when the temperature drops to 40° C.； and evenly and sufficiently stirring until cooled to obtain an ointment.
