Polyurethane/montmorillonite nano-composites were synthesized,and then used for fiber spinning.The viscosity of the spinning solutions,dispersion of montmorillonite in cast films and drawn fibers,as well as the mechanical properties of polyurethane/montmorillonite fibers were investigated.The results indicated that the viscosities of spinning solutions containing montmorillonite were lower than that of the pure polyurethane solution,and the viscosity of spinning solutions increased after standing 24 h at room temperature.TEM images showed that montmorillonite particles were dispersed at the scale from nanometer to micrometer in fiber matrix.Compared with pure PU fibers,the mechanical properties of polyurethane/montmorillonite composite fibers were not improved except that the elongation at break was slightly increased.