Magnetic influence on the crystallization and orientation of poly(trimethylene terephthalate) (PTT) were studied by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), and X-ray diffraction (XRD) during isothermal crystallization at 195 A degrees C under pulsed magnet. The results showed that the crystallization properties of PTT are changed under the influence of pulsed magnetic field. It should be emphasized that the pulsed magnetic field can be applied as a new method to control the crystallization and orientation of polymers.