The ballistic performance of Kevlar fabric impregnated with different shear thickening fluids (STFs) were investigated at various impact velocities. The SiO2 nanoparticle based STFs were reinforced with graphene and showed a significant increase in viscosity and shear thickening efficiency compared to pure STF. Ballistic experiments were performed on fabric treated by different STFs, and different failure modes including yarn slipping, extraction, and breakage in shear failure were obtained. To better understand how different STFs affect ballistic performance, single yarn pull-out tests were also carried out to examine the shear strength and friction between the interlocking yarns of fabric treated with STF. The results showed that STF reinforced with graphene is better at preventing the yarns from slipping, and the single yarn pull-out force is almost 5 times more than pure STF. Moreover, reinforced STF also has a significant influence on the ballistic limit and energy absorption of Kevlar fabrics. And the increased amplitude of energy absorption is almost 20% more than the pure STF/Kevlar load case. Combining with the energy absorption and different failure modes, the effect of STF on the failure mechanism of neat/treated fabric was also discussed.