Abstract <p>Knitted fabrics are widely used in flexible devices and wearable technologies due to their diverse mechanical performance. However, their tensile mechanisms in different directions remain unclear, resulting in costly optimization processes for customized mechanical designs. This study investigated the mechanical regulation of knitted fabrics by varying yarn elasticity and stitch pattern. Nine fabrics were knitted using three yarn groups and three composite stitch patterns. Their tensile properties were experimentally measured, and the stress transmission between loops in composite stitch patterns was further simulated by mesoscale finite element models. The results indicated that stitch pattern predominantly governed tensile behavior along the course direction, whereas yarn elasticity played a dominant role along the wale direction. Combining basic stitch patterns increased stiffness by 533.7% ± 21.2% at 60% strain along the course direction. Increasing yarn elasticity proportion to 30.6% ± 0.8% elevated stiffness by 57.5% ± 4.7% at 10% strain, but reduced it by 196.0% ± 11.0% at 60% strain along the wale direction. Finite element simulations further visualized stress distribution and identified distinct mechanical roles of single-faced courses (jersey and purl) and double-faced courses (full rib). The stress in single-faced courses was 239.8–460.8% higher than in double-faced courses during stretching along the course direction, while the opposite trend occurred along the wale direction. This study quantified and visualized the stretching mechanism of yarn and stitch patterns in directional mechanics, providing a theoretical and practical basis for customizing the mechanical performance of knitted structures.</p> Graphical Abstract <p></p>