How to form high-quality transverse inner ribs through power spinning is a key issue for complicated integrated curved generatrix parts with transverse inner ribs.In this study,the forming characteristics and laws during the power spinning process were investigated using a finite element simulation based on the orthogonal design method.The results show that the transverse inner rib distributes homogeneously along the circumferential direction but inhomogeneously along the generatrix direction.Depressions occur easily in the middle zone of the rib (MZR).The roller nose radius is the most significant parameter of the MZR underfill degree.A larger roller nose radius is helpful to decrease the MZR underfill degree.Furthermore,the preformed billet thickness also plays a vital role in the underfill degree of the front zone of the rib and the back zone of the rib,as well as the depression degree of the outer surface of the rib.By combining the ribfilling characteristics and laws,the optimized forming process window for obtaining high-quality inner ribs was obtained by regression analysis,thus laying a basis for improving the forming quality of curved generatrix parts with transverse inner ribs in power spinning.