Thermoplastic polyurethane (TPU) was thin film coated on polyamide 6 (PA6) fibers by the reactive bulk and solution coating techniques. The thickness of the coating was 40 μm for the reactive bulk coating technique and 20 μm for the solution coating. The increase in crystallinity, the formation of the interface interaction region and the entry of TPU thin film coating into the micro-cracks under tensile stress resulted in the increase of strength as well as elongation of the TPU coated PA6 fibers. The microphase separated-structure and the orientation of the hard segment domains of the TPU thin film coating on the PA6 fiber surface had an impact on the force alignment of the PA6 fiber when under a mechanical stress. The hard segment domains of the TPU thin film which was prepared by solution coating technique showed better alignment to the deformation force direction compared to the reactive bulk based one. This led to better mechanical strength of the former based TPU coated PA6 fiber. The TPU is a soft material and the improvement of mechanical property with same should be specially noted. So an understanding of both type of coating techniques is very useful in various industrial applications of PA6 fibers.