Abstract: It is essential to measure the stitch length of the weft knitted fabric in a static environment forsaving cost and improving productivity.The image inputted is dealt with the digital image processingtechniques:carrying out the transformation of grey scale;removing impurities with media filtering;abstractingthe character of the stitchlength with Fouriertransformtechnique;inducingtransformformula between2Dand3Dof stitch′s geometric model;and gettingthe value of the stitchlength.This provides a newmethodfor non-destructive measurement of the stitchlength.