Abstract: Stress intensity factor analysis of pipe cracks is the key to determine whether there exists crack propagation and to calculate the pipe fatigue fracture. The stress intensity factors at the double axial cracks' tip of pipes with different size, crack length and angles between cracks were calculated by universal finite element software ANSYS. The calculation results indicated that the stress intensity factor increases with increasing the angle between double axial-through cracks when the pipe size and crack dimensions are determined. The influence of angle between cracks on stress intensity factor is enhanced with increased ratio between crack length and pipe thickness at defined pipe size. The analysis may provide certain reference information for reasonable determination of the crack propagation and accurate calculation of the pipes' fatigue fracture.