In order to realize the forming of 3A21 aluminum alloy conical parts with small angle, two methods of multi-pass general strength composite spinning and preforming spinning were adopted, and the influence laws of process parameters such as blank size, wheel fillet radius and wheel clearance on the spinning results were studied. The results show that during the multi-pass general strength composite spinning, the smaller the relative thickness of billet is, the more obvious the trend of the thinning and cracking and the instability and wrinkling of flanges is. After spinning, the change of material wall thickness is U-shaped, and the thickness at both ends is about 7 mm as well as the thickness in the middle is only about 5 mm. However, the part is not well fitted to the die, and the maximum clearance is up to 0.9 mm. Through the combination of preforming and shear spinning, the blank will not produce the phenomenon of instability cracking, and the wall thickness is controlled more accurately. Thus, the wall thickness of the side wall for spinning part is about 7 mm, the wall thickness of mouth is about 11 mm, and the clearance between spinning part and die is very small with only about 0.2 mm.