Abstract: The finite element software ABAQUS was used to analyze the crack-tip stress field of the unidirectional fibre-reinforced composite plate mode I cracks, as we took the angle of the crack edge with the fiber orientation to be 0°, 30°, 60° and 90° respectively. The tangential normal stress intensity factor ratio criterion was applied to predict the direction of crack propagation and the factors to influence the crack propagation were discussed.The results showed that the stress concentration at the crack tip was obvious, and the stress decreased rapidly with the increase of distance from the crack tip. The orientations of the maximum Mises stress and the maximum tangential normal stress intensity factor ratio were the fiber orientation, the crack would grow along the fiber orientation. The crack was liable to extend with the decrease of angle of the crack edge and the fiber orientation or the increase of crack-depth ratio.