The optical phase retardation method was employed to observe the transient twist reorientation effect of a plane-aligned nematic liquid crystal induced by ultra-short laser pulses. The experimental result indicated that, although the electric field intensity of laser pulses is much higher than that needed for twist deformation, it does not ensure the twist reorientation under the laser pulse. This is because the width of laser pulse is very short and the response time for the twist reorientation is very long. To overcome this barrier an optimum angle (45°)between the polarization of the laser pulse and the director orientation in substrates is found by analysis.Using this initial angle, we observed a plane-aligned nematic liquid crystal cell doped with a few o-(D-Thr)N-C2-(TPP) to possess memory effect after the laser pulse pump, which was important in optical data storage and memory display.