OBJECTIVE： To prepare the Peppermint oil moisturizing microemulsion for nasal mucosa and survey its mucosal adhesion and cilia toxicity. METHODS： The polyoxyethylene hydrogenated castor oil was used as emulsifier to prepare the Peppermint oil moisturizing microemulsion for nasal mucosa， and the preparation technology was optimized on the basis of comprehensive score by orthogonal design. The microemulsion was characterized and the menthol content was determined by GC. The mucosal adhesion was evaluated by measuring the transport rate by cilia in vivo， and the cilia toxicity of microemulsion was evaluated by measuring the sustained movement time of cilia in vitro. RESULTS： The optimal preparation technology of self-made microemulsion was to firstly disperse the peppermint oil and the emulsifier， then add anhydrous ethanol， edible glycerin and distilled water， and stir at 1 200 r/min for 2 h. The average contents of menthol in the three batches of the microemulsion were 2.682， 2.507 and 2.496 mg/mL （RSD＝2.89％，n＝3）， respectively. The cilia transport rates in vivo were （0.65±0.01）， （0.78±0.03）and （0.92±0.04） cm/min in high-dose， medium-dose， and low-dose groups of self-made microemulsion （2.561， 0.256， 0.128 mg/mL of menthol） respectively， which were significantly lower than normal saline group and compound menthol nasal droups （P＜0.05）. The cilia movement time in vitro were（206.7±4.9）， （226.0±13.5）， （269.3±12.9）min， which were significantly longer than sodium deoxycholate group （P＜0.05）. CONCLUSIONS： The preparation technology of self-made microemulsion is easy-to-handle and controllable in quality. The prepared microemulsion shows good mucosal adhesion without cilia toxicity．