Concentration is a physical quantity characterizing the characteristics of solution.lts measurementhas important research significance in biomedicine ,material science and other fields.A real-time measurementsystem of solution concentration is built by using a self-made simple grating spectrometer.The use of doublebeams in the optical path is conducive to reduce the jitter of the absorption spectrum and improve the stabilityof the measurement system.The simple spectrometer combined with machine vision technology realizes thefunction of on-line concentration measurement. The working curve of absorbance a-concentration C isestablished by Lambert Beer law.The self-designed program measures the absorption spectrum of the sample tobe measured in real time to obtain the absorbance ,and measures the concentration of the sample according tothe working curve.The relative error of potassium permanganate solution concentration measured by the deviceis less than 1%,which shows that the measurement system can measure the solution concentration quickly andaccurately.