Abstract: Several factors affecting the spirality of aramid knitted fabrics made by the flat knitting machine were discussed. The experiments and theoretical analysis show that the spirality of aramid plain knitted fabrics is resulted mainly by the larger frictional coefficient of aramid filaments and the yarn's robbing back as the old loops casting-off the top of latch needle,and the spirality degree of aramid plain knitted fabrics is in inverse proportion to stitch length of the fabrics.