Orientation and interfacial stress transfer in cellulose nanocrystals (CNC) reinforced polyacrylonitrile (PAN) nanocomposite fibers were determined by Raman spectroscopy. The 1095 cm(-1) Raman band was used to quantify the orientation of CNC in composite fiber. Under VV (vertical/vertical) mode, polar plots of all composite fibers showed a two-fold symmetry. Under VH (vertical/horizontal) mode, it showed a four-fold symmetry. The CNCs are highly oriented in the composite fiber, which is confirmed by second and fourth order orientation parameters: < P-2(cos theta)> and < P-4(cos theta)>. The 1095 cm(-1) Raman band shift under uniaxial deformation was used to characterize the interfacial shear stress transfer between PAN matrix and CNCs. (C) 2017 Elsevier Ltd. All rights reserved.