To improve the formability of 3A21 thick plate, it must using the pre-formed blank to power spinning forming. There are many parameters involved in power spinning forming process and the forming process is complex. Spinning rollers is one of the critical technological equipments in  spinning forming process, which deeply effects the forming accuracy and forming quality of formed parts. To reveal the influences of above parameters on the spinning forming process for thick plate, using the method combated finite element simulation based on ABAQUS/Explicit with experiment analyzed the effect laws of spinning roller working radius, feeding rate of spinning roller and gap between spinning roller and mandrel on the wall thickness and fitness to die of spinning parts. The results show that the small spinning roller working radius makes it easier to embed rollers into plate, and the large radius may affect the fitness to die and uniformity of wall thickness for spinning parts. Besides, small feeding rate of spinning roller enhances the fitness to die of spinning parts and avoids local piling up to improve the uniformity of wall thickness. And an appropriate gap between spinning roller and mandrel contributes to material transfer and the fitness to die of spinning parts. Through the above research and experiments, proper spinning parts were obtained finally.