The　apparent　electrophoretic　mobilities　of　procaine　hydrochloride　(μi)　in　a　series　of　concentration　of　β-cyclodextrin　were　measured　directly　by　capillary　electrophoresis　technology.　A　new　mathematical　treatment　method　is　proposed,　which　based　on　the　fact　that　the　molar　ratio　of　the　inclusion　complex　was　1:1　established　by　spectrophotometry.　Using　the　proposed　method,　the　binding　constant　of　the　inclusion　complex　of　procaine　hydrochloride　with　β-cyclodextrin　can　be　obtained　easily.　The　determination　result　was　in　correspondence　with　those　of　the　spectrophotometric　and　fluorescence　methods.　©　2002　Elsevier　Science　B.V.　All　rights　reserved.