Abstract: Alternating elliptical axis tube can efficiently enhance the heat transfer. The cold forming process of the tube was numerically analyzed by a finite element model. The three-dimensional distribution of residual stress was investigated and the residual stresses on three representative sections were compared. The effect of the transitional angle of the die was analyzed. The results show that the maximum residual stress appears on the inner surface of the transitional region and the residual stresses on surfaces remarkably increase as the transitional angle of the die increases. Forming control parameters can be optimized based on the numerical results. Taking account of the heat transfer performance and the residual stress magnitude of the tube, a propositional transitional angle for industrial application is given.