Polymer-liquid crystal (LC) binary mixtures have two modes of concentration fluctuations characterized by the Ornstein-Zernike-Debye form with correlation length O (OZD mode) and Debye-Buche form with correlation length l (DB mode) (l > xi) in their one-phase region and isotropic state of LC. The temperature dependence of OZD mode exhibits the critical phenomena similar to common binary mixtures while the DB mode is almost independent of temperature. Under the condition where LC molecules oriented by electric field, the OZD mode is insensitive to the orientation while the DB mode is enhanced perpendicular to the orientation direction. These results indicate that the DB mode is induced by the orientation of LC molecules.