Addition of purple sweet potato flour has a negative effect on the technological characteristics of steamed bread. The present study researches the potential of extruded purple sweet potato flour (EP) in improving the quality of composite dough and steamed bread. Compared to unextruded purple sweet potato flour (UP), addition of EP significantly increased dough thermal temperatures and decreased the freezable water content, indicating that it enhanced the binding of dough components with water molecules. The rheological properties of dough height, extensibility, configuration ratio, and deformation energy of EP added dough were similar to wheat dough. Moreover, steamed bread made from EP had higher specific volume, lower hardness, and chewiness than their elaborated from UP. Furthermore, the total polyphenol content and antioxidant activity of EP were significantly improved in comparison with the UP and wheat steamed bread. In conclusion, results mightily suggest that the addition of extruded purple sweet potato flour could be an effective way of enhancing the technological and nutritional of composite steamed bread.