In this study, berberine hydrochloride (Ber) was used as model drug to prepare a sustained-release cold sol using hydroxypropyl methyl cellulose (HPMC) to achieve superior drug dissolution and transdermal absorption effects. For comparison, a Ber cold sol without HPMC was also prepared using the same method. The preparation process was optimized based on the in vitro release and transdermal permeability of the drug. The results indicated that 1.67 wt% Carbomer 940 and 1.33 wt% HPMC K100M were selected as matrix components with the best sustained-release effect, and drug dissolution of cold sol prepared by combination of these two matrices was significantly slower than the cold sol without HPMC. In addition, transdermal absorption result demonstrated that 0.67 wt% glycerin and 1.33 wt% peppermint oil were the best osmotic enhancers for the optimization of Ber sustained-release cold sol. Herein, HPMC K100M performed important functions in the external application of Ber.