In this study, the differences in the mechanical properties of PET and PTT warp knitted fabrics were studied, based on variations in the mechanical properties. The results of the research show that PTT warp knitted fabrics had lower flexibility than PET warp knitted fabrics which were opposed to the properties of the yams. However the results of bending and compression properties were almost similar in both PET and PTT warp knitted fabrics. Because the bulkiness of P1T yam compared with PET, the abrasion coefficient of PTT warp knitted fabrics was greater than that of PET. Thus, PTT warp knitted fabrics had some aesthetic differences compared with PET warp knitted fabrics, however, although the knitting conditions were similar.