Injection molded micro-fluidic chips are characterized by that their micro grooves show perfect imaging quality in height but not satisfactory in width, meanwhile the chip cannot remain the uniform quality for the width of micro groove everywhere. Therefore,this paper proposes an image processing system based on Matlab to process the micro flat photo of the micro groove of an injection molded micro-fluidic chip and to complete the non-destructive testing for the micro groove. In image processing,the artificial interference is introduced to eliminate the image noise effectively and the profile point extracted form the photo are used to fit the profile lines of the groove.Then, the opening width and bottom width of the micro groove are measured. Measured data of microchannel widths from the micro flat photos are compared with those data obtained from cross-sectional photos of microchannel slices. Results indicate that the differences between the two measuring ways are less than 4% for the opening width and less than 3% for the bottom width, respectively. Obtained data demonstrate that the proposed non-destructive method based optical telescope can meet the requirements of micro-fluidic chips for measurement of molded quality in injection molding.