lt constructs an experimental device for measuring Liquid concentration based on total rellectionprineiple. With the help of self-developed digital image processing technology,the angle is measured collectedby the high-definition camera, the refractive index of transparent liquid is obtained, The concentration iscalculated according to the Monotonie funetion relationship between the fiting liquid coneentration and itsrefractive index. The experimental prineiple is simple, the experimental deviee is easy to operate, and the aecuracy is high.The innovation ability of students has been cultivated in college physics study.