Yarns with high performance are more and more widely used in geotextiles. In this paper, the author researched the effect of twist on the tensile behaviors of high performance yarns. Due to the superior tensile strength of these yarns, the tensile tests can’t be operated on the normal textile yarns testing machine and all yarns were tested on the fabric strength tester. The results reveal that the tensile strength of yarns will firstly increase, and then decrease with the increasing twist. The simple analyses were also proposed to demonstrate this phenomenon.