Abstract: To investigate the biaxial tensile performance of weft knitted fabrics and the effect of fabric parameters on the stress-strain curves, four types of weft knitted fabrics were tested on an instrument whose clamps can move in the two directions. The results show that under the same condition, the stress-strain curves of plain knitted fabrics with different yarns are quite similar. Fabric structures mainly affect the tensile property; the tensile property varies with density. Fabric tensile property can be improved by finishing.