The mol. structure of ropivacaine hydrochloride was studied by IR(MIR) spectroscopy(including:one-dimensional MIR spectroscopy, second derivative MIR spectroscopy, fourth derivative MIR spectroscopy and deconvolution MIR spectroscopy).The ν_(asCH_3-Ropivacainehydrochloride), ν_(asCH_2-Ropivacainehydrochloride), ν_(aCH_3-Ropivacainehydrochloride), ν_(amide-I-Ropivacainehydrochloride), ν_(amide-II-Ropivacaine hydrochloride), ν_(amide-IV-Ropivacaine hydrochloride), δ_(asCH_3-Ropivacaine hydrochloride), δ_(sCH_3-Ropivacaine hydrochloride), δ(CH_2-Ropivacaine hydrochloride) and ρ_(CH_2-Ropivacaine hydrochloridewere) found also.It was found that the mol. structure of ropivacaine hydrochloride could be distinguished by MIR spectroscopy.A new methodol. was established for the study of ropivacaine hydrochloride structure, which has application research value.