Polyurethane (PU)/nylon 6 blends were prepared by melt blending with Haake Rheomix at $250^{circ}C$. The compositions of PU/nylon 6 blends were 10/90, 20/80, 30/70, 40/60, and 50/50 (wt%). The effects of PU contents and blending time on the crystal structure, tan $delta$, the tensile properties, and the impact behavior were investigated by means of WAXD and DMA, etc. The crystalline diffraction peaks are broadened, and their intensities are reduced with increasing PU contents and blending time. The glass transition temperature, the tensile strength, and the tensile modulus of the blends are also decreased and the elongation at break is increased. The influence of PU content on the crystal structure, tan 3, and the tensile properties of PU/nylon 6 blends is more significant than that of blending time. The impact strength of PU/nylon 6 (10/90 wt%) blends measured at 20 and $-35^{circ}C$ could be greatly improved.