Abstract: In order to simplify data processing of ash content and image gray value of flotation tailings and reduce work of designer,Matlab CFtool is used to fit curve given by ash content and image gray value of flotation tailings,and then function relationship between ash content and image gray value of flotation tailings is built after verifying fitting result. The result shows that CFtool is well suitable for processing data with high accuracy of fitting data,which can decrease greatly the work of designer.