Abstract: The stress concentration factors for the unidirectional solid and hollow fiber reinforced composites subjected to transverse,shear,longitudinal loads are computed with taking the basic properties of the fiber and matrix into account in micro-state by finite element method,The paper gives numerical results in graphical form varying with the fiber volume content and value of E^f/E^m,and emphatically discusses the stress concentration factor in longitudinal tension.The results show as following.1) The stress concentration factor of unidirectional solid fiber composites is,in general,greater than that of the a nidirectional hollow fiber composites under transverse or shear load.2) The maximum stress concentration factor resulted from shear load occurs at bond face,that is,the bond face is weak area.3) The unidirectional hollow fiber composite is inferior to the unidirectional solid fiber composite in longitudinal tension,but its longitudinal stress gradient at bond face is smaller than that of the unidirectional solid fiber composite.