Nasal mucus is the primary barrier affecting the nasal absorption of vaccines and drugs. In vivo assessments are difficult to perform due to the complexity and variability of the confounding factors,whereas in vitro evaluations are mostly used. The existing in vitro assays for monitoring nasal mucus permeability of drugs,such as cell model assays and multiparticle tracer techniques,have the disadvantages of a long cell culture cycle,cumbersome operation,high cost,little available information,and the need for fluorescent labelling,which have great limitations for the in vitro evaluation of nasal mucosal formulations. Therefore,there is an in urgent need to establish a rapid,simple and sensitive method for the evaluation of mucus permeability of nasal mucosal formulations. Based on the sensitivity of ATR-FTIR spectroscopy to changes in drug structure and mucin secondary structures,the nasal mucus permeability of liposomes, typical lipid nanoparticles,with different properties (particle size and charge) was studied in this paper,and the interaction of different liposomes with mucin in mucus by FTIR spectra to establish an in vitro evaluation method for mucus permeability of nasal mucosal preparations. Methodological studies showed that for PEG10000,chitosan,and sodium alginate liposomes,the linear relationships of the method were Y=2.386 6X+2.154,Y=1.870 3X+0.278 9,Y=1.130 14X+0.060 9,the linear correlation coefficients were 0.995 8，0.994 5，0.990 9,and the precision RSD values were 0.62%,0.73%,and 0.95%,respectively; the RSD values in the repeatability experiment were 0.83%,0.97%,and 0.88%,respectively. It is indicated that the method has a good linear relationship,high precision,and good repeatability and can be used to evaluate the permeability of pharmaceutical preparations in mucus in vitro. The results showed that the sample absorption bands with increasing intensity of different liposome formulations could be obtained by scanning the samples at different times in interaction with mucus using ATR-FTIR. For PEG liposomes with different particle sizes,the smaller the particle size,the stronger the mucus permeability; for liposomes with different charges,chitosan liposomes with positive charges have the weakest mucus permeability,followed by sodium alginate and PEG liposomes have the strongest mucus permeability. Further studies have shown that the difference in mucus permeability of liposomes with different charges stems from their interaction with mucins,and this conclusion can be obtained by analyzing the information on each secondary structure (α-helix,β-sheet,β-turn,irregular turn) contained in the mucinamide Ⅰ band (1 600～1 700 cm-1). In summary,the in vitro evaluation method established in this paper based on ATR-FTIR is sensitive and simple and can be used as a rapid assay of nasal mucus permeability for various preparations. And with improved applicability,it can also be used to evaluate the permeability of pharmaceutical preparations in other mucus,which has a broad application prospect.