A method on the determination of caffeine in beverage with acridiene orange-${eta}$-cyclodextrin (CD) inclusion complex was developed. The conditions such as pH of the sample solution and concentration of acridine orange and ${eta}$-CD were optimized to 12.0(${pm}0.5$), $1.9{ imes}10^{-6}M$ and $1.25{ imes}10^{-3}M$, respectively. Under these optimum conditions, the calibration curve of caffeine was obtained over concentration range of $5{ imes}10^{-5}{sim}1.1{ imes}10^{-3}M$. The detection limit was $1.0{ imes}10^{-5}M$. The relative errors(%) in beverage samples were less than 5.0%.