Abstract: Since the stress concentration analysis of weld angular distortion in spiral welding pipeline concerns complicated three-dimensional mechanics issues, there are no formulae and methods available for it in published literatures. Mechanics model for the stress analysis of spiral weld angular distortion has been established in this paper. Based on the reported theoretic formulae for stress analysis of straight weld angular distortion, additional bending stress and the maximum stress calculation formulae due to spiral weld angular distortion were suggested through combining theoretic analysis with FEM simulation calculating and validating. The determination method for limit of spiral weld angular distortion was given to provide theoretic basis for quality control and safety assessment of spiral welding pipeline.