An imaging method to measure the geometrical parameters of contact lens is put forward. In imaging method,contact lens is projected into an enlarged image with a projecting lens. An imaging sensor is used to acquire the enlarged image,and a single board computer is adopted to process the image and to do the calculation of parameters. In addition,a glass ring emerged in the liquid was introduced to hold contact lens without any distortion or dehydration. An example of system is provided. With the system,the thickness t can be measured directly,and fore radius r₁ and retral radius r₂ can be calculated with the help of h₁ and h₂ and d₂ and d₂. With an imaging system of 20 times magnification,and a 512 pixels CCD linear imaging sensor of a 50 μm pixel spacing,the system has a resolution of 5 μm,which is much higher than the accuracy requirement of measurement 0.O1 millimeter.