Abstract: Four kinds of weft knitted fabric with different constructions were produced with glass fiber yarns on an electronic flat knitting machine and used for reinforcing the weft knitted composites by VARTM process.Tensile tests were carried out in the course and wale directions.The mechanical properties of the composites were investigated by analyzing the stress-strain curves.The influence of tuck loop and float on the tensile properties of weft knitted fabric reinforced composites was investigated.The results reveal that the degree of orientation and numbers of load-bearing yarns in two directions are major factors influencing tensile properties of four kinds of weft knitted fabric reinforced composites.The damage modes show that the weft knitted fabrics made from glass fiber yarns have good bonding with resins and thus have potential values for applications.