Abstract: This paper aimed at studying the effects of hyaluronic acid (HA) with different molecular weights on the transdermal absorption and retention of reduced glutathione (GSH) in the isolated skin of SD rats. Franz diffusion cell method was used to investigate the effects with different molecular weights HA on the in vitro transdermal penetration of GSH and the storage in different layers of the skin. AutoDock molecular docking was used to study the interaction between GSH and HA. Attenuated total reflection Fourier transformed infrared spectroscopy (ATR-FTIR) and H&E section staining were used to characterize the changes and effects of lipids and proteins in the rat stratum corneum after HA acts on the skin. The results of in vitro transdermal experiments showed that HA with different molecular weights had a significant impact on the amount of GSH passing through the skin, that as the molecular weight of HA increased, the effect of preventing GSH from passing through the skin became stronger, that in terms of skin storage, HA with different molecular weights could increase the storage of GSH in the stratum corneum, and that HA with a molecular weight below 7K could also significantly increase the storage of GSH in the dermis. The molecular docking results showed that HA and GSH had a relatively strong interaction, which could form intermolecular hydrogen bonds; and the results of ATR-FTIR and H&E staining showed that HA could interact with lipids and keratins in the stratum corneum of the skin. Such interaction can increase the permeability of the stratum corneum of the drug, however, as a water-soluble GSH, it may be involved in the formation of intermolecular hydrogen bonds with HA. In the structure of HA hydrogel, the amount of GSH drug passing through the intact skin is reduced; but at the same time, this interaction also provides a reservoir for the formation of GSH, thus increasing its storage in the skin. Through comparison of the storage capacity of GSH in the stratum corneum and dermis of the isolated skin due to the increase of HA with different molecular weights, it has been found that the storage capacity of HA with low relative molecular weight is the best.