Structural and morphological behavior of solution grown nylon 4,6 crystals has been determined and compared with other polyamides, especially nylon 6,6. The lath shaped crystallization products, aggregated in the form of sheaves, possessed the characteristics of chain folded single crystals. The measured layer thickness by small angle X-ray diffraction varied with crystallization temperatures. The dependence of the layer thicknesses on the crystallization temperatures showed a horizontal plateau followed by a monotonous increase with the high crystallization temperature(T_C ) of about 130 ℃. The comparison of wide and small angle : X-ray reflections combined with the examination of electron diffraction patterns of sedimented mat of crystals shows that the chains in the nylon 4,6 are perpendicular to the lamellar surface and the 001 planes are inclined to the fold surface, which are quite contrast to other polyamides where tile chains are inclined to the lamellar surface and the 001 planes are parallel to the fold surface.