Abstract: The kinematic characteristics of rotary blanking without press rollers was researched, and then a design scheme of dies was put forward for sheet metal rotary blanking. Finite element simulation of 45# steel sheet rotary blanking processes was performed by ABAQUS software based on shear failure criterion and arbitrary Lagrangian Eulerian adaptive meshing method, and the influence of technical parameters on machining quality was analyzed according to this simulation result. It is found that the front and rear cutting edges of square holes undergo five stages during rotary blanking:metal sheet bending, punch indentation, crack initiation and propagation, material fracture and separation, and punch pullout. Quality defects in rotary blanking processes appear as perpendicularity, burr, corner collapse, indentation, etc. The main factors which influence cutting quality perspicuously include nominal clearance, punch height, roller radius, and so on. Decreasing the nominal clearance, lessening the punch height and enlarging the roller can improve cutting quality, especially are good to cutting perpendicularity and burr height. For carbon steel such as 45# steel, the nominal clearance of the rear cutting edge should be 5% to 10% of metal sheet thickness and this value of the front cutting edge can be smaller. The roller radius should be 100 to 150 times greater than metal sheet thickness. On the condition that the metal sheet could be fully separated, the punch height should be as small as possible.