OBJECTIVE： To prepare Ambroxol hydrochloride hydrogel patch and study its transdermal permeability in vitro. METHODS： Polyvinyl alcohol （PVA）， aluminum glycinate and polyacrylic acid sodium （PAAS） were used as excipients to prepare Ambroxol hydrochloride hydrogel patch. Based on single factor experiments， using appearance and property， initial bonding strength， endurance bonding strength and peel strength as indexes， Box-Behnken response methodology was used to optimize the amount of PVA， aluminum glycinate and PAAS. Validation test was also conducted. The transdermal permeability in vitro of prepared hydrogel patch was investigated by Franz diffusion cells. RESULTS： The optimal prescription was as follows as PAAS 2.35 g， aluminum glycinate 0.1 g， PVA 1.0 g. Comprehensive score of 3 batches of hydrogel patch were 9.4， 9.5， 9.7， respectively； relative errors were 2.08％， 1.04％， 1.04％ compared with the predicted values. Within 24 hours， the transdermal rate of ambroxol hydrochloride was 9.472 μg/（cm2·h）， which was up to zero-order kinetic model （r＝0.994）. CONCLUSIONS： Hydrogel patch formula is reasonable and shows good transdermal properties. Its transdermal absorption meets zero-order kinetic process.