We have investigated the reorientation of NLC In thermal gradient field. The nonuniform temperature field is produced by focusing He-Ne laser on a dye doped homeotropically aligned LC cell. A new physical mechanism is proposed, where the reorientation is resulting from the surface torque produced by order-electric effect. The calculation of free energy shows this configurational transition is second order. The theoretic analysis and experimental observation of reorientation induced by angular momentum of light field in dye doped NLC are also reported.