Penetration experiments are studied for Zr-based metallic glass composites containing four kinds of tungsten fiber with different diameters to perforate homogeneous armorSsteel at velocity 1270m/s±40m/s, in which the characteristics and depths of penetration is analyzed compared with the tungsten alloy. The results demonstrate that under the same preparation technology, the diameter of the tungsten fiber is a critical parameter for penetration ability. Firstly, the curve of the diameter of the tungsten with the penetration depth is convex when it perforates ideally and the composite containing 0.7mm tungsten fiber obtain the maximum penetration depth of 55mm which is increased by 25% compared with tungsten alloy because the failure mode is failed with adiabatic shear failure during the penetration similar with the depleted uranium alloy appearing a crater 90° at bottom. Secondly, the diameter of tungsten fiber influences the failure mode of the head of the composites significantly. As the increasing of the tungsten fiber diameter , the failure mode ranges from composite failure mode that includes deformation, splitting, bending and crack to adiabatic shear failure and then it turns to composite failure mode again.